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Ailing Modern
Aeolian Player
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Ailing Modern Aeolian Player

Below are some of the exchanges I had with the owner of an Ailing Modern Aeolian Player. I attempted to take him on a step-by-step evaluation of his player in an effort to discover the root of the problem. Unfortunately, he was stuck on thinking he knew what was wrong and he didn't do a number of the things I recommended. As a result, I believe he ended up spending his money unwisely. If used as suggested, the information in this web page will lead you to the heart of the problem.



I have an Aeolian (The Sting). I think I need to have the vacuum pump repaired or replaced. The piano will play but is slow, if I help with foot pump it works.

My Reply:

I'm more inclined to believe that the unit has a variety of problems that aren't related to the vacuum pump -even though that is a slight possibility.

Common problems include poor action regulation, reservoir bellow leaking, stack bolts loose, leaking air motor, one or more leaking block valves, and missing or leaking caps on one or more of the block valves on the vacuum pump.

There are no replacements for the Aeolian vacuum pump, but a more powerful motor can be installed in the box -although it is not recommended. The problem is the volume regulating device that Aeolian used. It was designed to operate at a maximum of around 30 inches of water vacuum. So, the vacuum pump motor they used produces about 35 inches at maximum. (Most of them produce around 28 at maximum.)

One key thing you mention is that the music plays "slow". Basically, there are three things that can cause that problem. One, a leaking air motor. Two, a leaking air motor governor bellow. Three, a forward roll brake that has become contaminated with grease. (That's another fairly common problem.) Of the three, I would suspect the air motor first. The Aeolian air motor has a bad reputation for leaking internally. While it looks fine, it uses tons of vacuum and does very little work.

You can test it by removing it from the piano and sucking on the vacuum flange -where the hose connects. As you're doing that, hold the crankshaft and stop the motor from turning. Don't worry, you won't break anything. If the motor is working well, you won't be able to suck any air when you stop the crank from moving -which indicates that the unit is air-tight. What will most likely happen is that you'll be able to suck vast amounts of air after you stop the crank from turning -indicating massive internal leakage.

BTW, I've written an article on how to seal the internal vacuum passages in this motor. It's at:


Hope this helps.


John A Tuttle



I think the main problem is the vacuum pump, I am quite sure it is original. Do you sell a vacuum Gage to test it. In any case I am sure it at least a major part of the problem, I can hear no leaks.

My Reply:

Here's a link to the least expensive vacuum gauge I could find on the net that will do the job.


Normally, I don't disagree with people, but I have nearly 40 years of experience working on the instrument you have, and you can never "hear" the leaks.

Personally, I think it would be less expensive for you to send me the pump and let me test it. I'll test it for free. (It takes one minute.) All you pay is the postage.



First of all, Happy Thanksgiving.

I pulled the air motor. and I can draw air through while preventing the motor to turn, so I guess it is leaking. I will send it to you for repair.

I guess I have your address somewhere, but let me know again, and the price, I am sure I have that also in one of your emails.

Will send it as soon as you contact me.

My Reply:

My mailing address is:

John A Tuttle
407 19th Ave
Brick, NJ

If all I have to do is seal the internal vacuum channel, the price will be $95 for labor plus whatever it costs to ship the motor back to you. I normally insure motors for $650.00.

If there are other problems, I will let you know as soon as I test the motor.

Lastly, I do require payment in advance of starting the work. So, please send a check for at least $95.00, made payable to John A Tuttle.

My Email After Receiving the Air Motor:

The air motor arrived and it was tested. I've uploaded a video to YouTube which explains the main problem.

As it turns out, the main vacuum channel is in very good shape. Almost no leakage at all. But, in the interest of completeness, I will seal it anyhow.

The main job will be re-surfacing the block (or manifold) and the sliders, so they are both perfectly flat. I will be shooting a video of that job so you can see how things progress. (Watch the video)


So, is this enough leakage to cause a slow play, or do you think the problem is elsewhere?

Good video!!

My Reply:

Yes, this will definitely have an adverse effect on the Tempo of the music -make it run slower. And, the motor has almost no power. So, it has to use more vacuum to compensate for the lack of power. (The leakage rate is just as bad as it would be if the manifold had the sort of leakage I mentioned before, i.e. cracks in the wood.) The end result is the same.

My Follow-up Reply:

I finished the preliminary resurfacing of the manifold. What a difference!!! Now the motor runs on TWO INCHES of vacuum. It has a small 'lope' because it evidently sat unused for a number of years. I hope to work most of the lobe out by running the motor for a couple of hours. There are also tiny pin hole leaks at the folds in the bellows, but nothing to get excited about. I figure the motor has at least ten years of good life... maybe more if it gets used at least 10-15 minutes a month --- to keep the bellows material from getting stiff.

Another Follow-Up Email:

Well, I checked the lope in the motor first thing this morning, and it's still there. After all the exercise the motor had yesterday, the lope was barely noticeable.

I uploaded another video that shows the burn-in, the adjustment of the sliders, and the lope.

It's too bad you can't see how fast the motor is actually spinning. If I had to guess, I'd say the RPM is around 2000.

As a final thought, I don't believe the lope will be noticeable when the music is playing. That's because there is about a 10:1 gear reduction and all of the drag associated with the transmission, take-up spool, forward roll brake, and the weight of the music paper. I've seen motors in lots worse shape (lope wise), and once the music started playing, the Tempo seemed nice and even.

Also, looking at the time stamps on the videos I shot while resurfacing the block and sliders, it took me just over two hours. (I have well over an hours worth of video that shows all the work done to resurface the block and sliders. I'll put that all on a CD or DVD and send it to you with the motor.)

Email Sent When Air Motor Was Returned to Owner:

If you're still experiencing problems with the volume of the music or sluggishness during large musical passages, try tightening the two nuts on the bottom of each end of the stack. They are usually in need of tightening. Beyond that, I would run a test roll and find any valves that aren't seating well. You can also adjust the main volume control at the vacuum pump.

2nd Follow-up Email to Owner:

If you don't already have it, I recommend the Aeolian Service Manual:



Just got the air motor, I installed and played a couple of rolls. It is much better, but it is still seems low on vacuum on fast songs. I will have to get a vacuum gage. What should be min. vacuum in inches.

My Reply:

My vacuum gauge goes from 0-200 in., but 0-100 in. would be fine.


The piano plays better, but it still lacks vacuum. Is a vacuum pump available, I saw one on your site, size 8 X 8 X 10 I believe, how accurate are those dimensions. I checked my available area a few years ago, and I think the height may be a problem, but I will check again before ordering.

I don't need the volume control, or the auto reverse, as I already have that, just the pump.

My Reply:

I have a web page that shows the exact dimensions at:


FYI, you can turn the pump sideways if you want. It doesn't have to stand with the supply flange facing upwards. And, since you have flexible supply tubing, getting it connected to the reservoir will not be a problem.

As you can see in the picture, the controller is wired into the pump box. I do not sell parts of the kit. It's only available as a full kit, and the only part you won't need is the flange. You need all the other parts for the kit to work properly.

Now, if you want, you can take the pump apart and put the motor into your pump box, but I don't know what the result of that change might be and it will most certainly void the guarantee. Also, without the controller in the circuit, the vacuum level of the motor increase to about 80 inches of vacuum. That's three times more than your piano was designed to handle....

FYI, one note of caution. If you use a higher level of vacuum than the piano was designed to handle, it will have an adverse effect on the air motor governor. But you should be able to solve the problem by increasing the tension on the air motor governor spring.


At this point, the owner decided to buy the Electrification Kit that I sell -even though I recommended otherwise. So, I sent an email explaining how the kit should be used or installed.

My Email to the Owner:

Basically, you remove the old motor and wiring from the existing box and install the new motor and it's wiring in the old box.

The beauty of doing the job as explained below is that you will gain two features that the existing system never had without losing any of the features it already has.

The job requires that you disconnect all of the wiring in both boxes. So be sure to mark everything so it can go back together exactly as it came apart.

You might have to enlarge the hole (for the electric wires) in the old box because it's probably too small to accommodate the extra wires for the new motor.

Usually, the rubber seal on top of the motor was glued onto the motor with contact cement -but not always. If the two seals (the one from the old motor and the one from the new motor) look identical, use the new seal.

Supporting the motor in the box is critical. Usually, slivers of wood (or veneer) are used to 'hold' the motor so the seal presses fairly tightly against the top of the pump box. And since the two motors aren't exactly the same height, you'll have to experiment to get a good tight seal.

The power cord for the new pump will plug into the existing receptacle as the old pump. That way you will maintain the automatic shut-off and power-on operations. Once the job is done, the power switch on the new controller will stay 'on' all of the time -unless you turn it 'off' to protect the circuitry from a lightning strike or major power surge.

The microswitch (in the kit) has to be installed up near the transmission so that it turns 'on' and 'off' as described in the installation instructions. This will give you one feature that the existing system doesn't have, and that is the ability to control the speed of rewind. How the controller is to be adjusted for rewind is explained in the installation instructions.

The other feature which you will have is the ability to control the volume of the music far beyond that which was available even when the existing system was brand new. That's because the controller has a variable speed control. So, the pump doesn't have to run at full blast all the time -like the existing motor did.

As for adjusting the Play Volume, I would do it as follows. Turn the Volume Control in the Spoolbox to 'Lo' and put on a fairly aggressive music roll. Set the Volume Control on the Controller to about mid-range. Depending on how loud the music is playing, turn the volume control on the Controller up or down so the music plays softly or slightly louder. Now test the Volume Control in the spoolbox. Unless I miss my guess, the Volume Control in the spoolbox will work as advertised. This will give you a quick way to change the volume of the music without re-adjusting the Controller. However, if you want, you can adjust the Controller to a higher level at anytime. Just understand that the levels set by the regular Volume Control in the spoolbox are based on the setting of the level of the Controller.


Owner (upon receiving the kit):

Just received the pump. The box is smaller than advertised. unless they considered the hose connection in the dimensions.

So, my question is, can I use the new box, as the motor fits nicely into the new box and hook the old wires to new box?

My Reply:

Before I can advise you any further, I need to see a picture of the existing pump.



I have not started to take the old one out, will do that tomorrow. I had it out a few years ago, it did not look like this one.

I will email you a picture when I get it out.

I just figured if I could put the new pump in the old box, I could see no difference than hook up the old pump wires to the new box. but you know better than I.

My Reply:

As I said from the beginning, the pump you bought is NOT a direct replacement for the existing Aeolian pump.

I want a picture of the pump while it is still installed in the piano. Seeing a picture of the pump after it is out of the piano is of no use to me.



Here are some pictures:

My Reply:

Here are some pictures of the top of the existing motor. What's under the metal valve assembly and inside the pump box (top)?

In a subsequent phone conversation, he admitted that he had forgotten how complicated the Aeolian pump box was, and took my advice to swap out the old motor in the original box for the new motor in the new pump kit. Unfortunately, he didn't follow my instructions and somehow connected the wires up incorrectly. Sadly, he burned up the controller, which costs $185.00.


I think it's very sad that the customer never did take the recommendations I gave him concerning other things he could do to improve the performance of the system. It was also found that one of the four volume control valves on the pump was missing its seal -which created a large vacuum leak. And while the system is now capable of playing music from soft to VERY loud, it's my sincere opinion that it would have been less expensive and a lot less involved if he had hired a professional player technician to repair his player piano.

If the vacuum level at the cut-out is only 11", there are at least four possible problems.

First, I'd disconnect the vacuum pump and measure the output of the pump.

Second, I'd disconnect all of the tubing that's connected to the exhauster assembly and test it to see how long it will hold a vacuum. The bare minimum is 12 seconds. It should hold a vacuum for over 30 seconds.

Third, check the integrity of the devices that are connected to the exhauster assembly. Namely, the play-rewind device and the tracking device.

Four, check the integrity of the bass and treble soft devices. (Sometimes they get their supply vacuum from the exhauster assembly. Most often, they get their supply from the stack.)

In other words, by process of elimination you determine where the vacuum is going. The pump should produce 28" inches of vacuum with nothing connected to it. If it doesn't remove the pump from the box and check it independently. It's possible that when the piano was dropped, the motor shifted in the box, and the upper seal is no longer tight.

BTW, are all four of the seals good on the four valve blocks on the pump? They must be 100% air-tight. If in doubt, cover the exhaust ports with duct tape.



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This page was last revised March 2, 2013 by John A. Tuttle, who Assumes No Liability
For The Accuracy or Validity of the Statements and/or Opinions
Expressed within the Pages of the Player-Care Domain.
Cartoon Graphics by E7 Style Graphics (Eric Styles)

Since "Player-Care" is an internet business, I prefer that we correspond via E-Mail (click here to fill out the 'Request Form'). However, if I'm not in the middle of some other activity, you can reach me at 732-840-8787. But please understand that during the hours from 8AM-5PM EST (Mon-Sat), I'm generally quite busy. So, I probably won't answer the phone. If you get the answering machine, please leave a detailed message stating the reason for your call. Also, repeat your name and phone number clearly and distinctly. By necessity, I prioritize everything in my life. And, if you call and just leave your name and number, and ask me to call you back, it might be a day or two before I return your call. Why? Because I don't know why you want me to call and I might not be prepared to assist you in an effective and efficient manner. If you leave me an E-Mail address (which I prefer), spell it out phonetically. The more you do to help me, the more I can help you in return. Don't rush. You have four minutes to record your message.

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