Hi all,  I would like to get some feedback from the readership on an
intermittent problem: a knocking Ampico B pump.  Said pump was rebuilt
in 2010 and was nicely quiet before and after the rebuild.  It went to
the Buffalo AMICA convention and performed very well during and after
the convention.

About a year later the pump started to knock after an Ampico roll with
a loud passage was played.  Average volume Ampico rolls and quiet rolls
brought no unwanted noises, but play a louder than normal roll (crashing
chords) and the knock is audible at the end of the roll and during
reroll.  Once the knocking starts it will continue, no matter what
loudness of roll is played.  Stop playing the piano for a while and
when it starts again, all is quiet.

What has been done to the pump:

a. The pneumatics have been recovered using good quality middle-weight
bellows cloth.

b. The bushing material has been replaced twice with appropriate
thickness material.

b. The posts to which the arms are connected have been checked for
looseness and none appear to be loose.

Any thoughts?  Thanks very much for your input!

Best wishes,
Mike Walter