In the attached picture, the red felt shows the start of the
channel that leads to atmosphere when the expression step is activated.
While rebuilding I noticed that this channel was blocked on three of
the units I have.  The blockage prevented the expression level from
latching.  I tried to locate the blockage to the extent that I drilled
out the factory-installed plugs but could not locate the proper
channel.  I wonder if others have encountered this problem.

In the second photo there is an unusual small bellows circled that is
attached to the main bellows by way of a metal link.  The main bellows
controls the vacuum to the stack (loudness).  The small bellows opposes
the large bellows and would slightly quiet the piano.  I have not seen
this before and wonder where it may be connected.  Perhaps it is
connected to the damper pedal circuit, or to the amplifier, or what?

Bill Chapman
La Quinta, Calif.

 [ A blocked channel leading to atmosphere via the valve
 [ http://www.mmdigest.com/Attachments/16/02/05/160205_122720_IMG_1652%20small.jpg 

 [ A rare little adjustment to the vacuum regulation
 [ http://www.mmdigest.com/Attachments/16/02/05/160205_122720_IMG_1649%20SMALL.jpg