The 'Ukelano' attachment is operated by a choke-type cable under
the keybed on the left hand side of the piano. It is also known
as a 'Honky-Tonk' or 'Mandolin' feature. To activate the feature,
pull the black knob outwards. If you open the top of the piano,
you can see an aluminum rail that's positioned between the piano
strings and piano hammers. To it is connected a piece of felt, in
the bass section, and a piece of heavy cloth, in the tenor and treble
sections. The cloth is cut in such a way that a 2" piece dangles in
front of each hammer. To each piece is connected a piece of tin.
When in service, the hammer hits the tin piece and it, in turn,
strikes the strings, creating a "rinky-tink" sound similar to that
of an old piano with very hard hammers.
I do not advocate the use of the Ukelano attachment on a regular
basis as it will disfigure the shape of the hammer heads over time.