Hi,  I had the same problem with an old two-tier Cable I rebuilt a few
years ago.  It also has the "silencer" or fast forward.  Art Reblitz
suggests that the functions be separated -- probably the best way.

I got away with not separating the functions by removing a latch (or
the stop) underneath the keyboard that forced you to pull down on the
lever slightly before the piano would go into rewind.  Even with this,
the pneumatic had to pull quite a distance.

The first thing I would recommend is that your tech be sure that the
rewind pneumatic has a _constant_ source of suction.  It _will not_
work with "stack residue suction" as Player Piano Company suggests.
If it still refuses to work, increase the hose diameter going to the
pneumatic if possible.  Next, if that still don't work, Install a
outside valve to amplify the signal.

If that thing still refuses to work, throw the thing out and try
this (maybe you could use the unit for auto sustain instead):

My favorite method of adding an "auto rewind" Is by installing a
solenoid (with action cloth glued to the moveable part to prevent that
"click" when the solenoid fires) triggered by a microswitch on the #1
stack pneumatic.  This system is not dependent upon the suction level.

This is wired to work even when the suction motor is off, as long as
the piano is plugged in to the wall.  As long as that stack pneumatic
collapses, it works every time.

Just because PPCo advertises a certain thing will work, it has been
my experience that quite a few concessions will have to be made before
it does.  Every player is different enough that it sometimes takes a
little time to get it to do what you want.

Andy Taylor - "The Lone Arranger"
Tempola Music Rolls Ltd.