Luke Myers asked about converting a simplex unit pneumatic to one
with a separate primary/secondary valve system [171231 MMDigest].
I suspect the disassembly of the unit pneumatic appears daunting.
Hmm; well, it is!

When built, the Simplex was a very advanced, flexible system.  If
a note failed, one could just replace that pneumatic by taking some
screws out and putting in a new one.  Usually the "note lifter" is
a metal piece screwed on and can be positioned anywhere along the
pneumatics' edge to accommodate the piano action.

The "main chest" on the Simplex is just a long rectangular box, which
is drilled to mount pneumatics in whatever configuration the piano
needs -- a very flexible, repairable system.  Nowadays, however, new
unit pneumatics aren't available from the factory, so one has to find
good ones or rebuild the ones in hand.

Speaking of rebuilding, I understand that cotton-based pneumatic cloth
is no longer available.  It is getting harder and harder to find good
materials for rebuilding/restoration, and more costly.  I recently
repaired (but not in the manner Luke mentions) a Manualo, and just the
air hose to the roll motor cost $90.  I'm beginning to understand the
use of clear plastic hoses! <sad smile>

When I say repaired, this is a piano that has been in the family for
it's entire life; however early on it was in a house with a coal-fired
furnace and everything had coal dust on it.  Yeech!  So I cleaned it
out, filled hammers, did some action regulating and found that the
notes played well, except where the hoses were broken, and the main
bellows kept up vacuum for about a minute.

So, I retubed the action and rebuilt the roll motor and tracker
pneumatics, which had holes.  The stack responded nicely at 4" vacuum
with only two valves needing cleaning, and one pneumatic leaking (not
through the cloth though!); I decided it was only one note, and
working, and the customer wasn't ready to do a full rebuild.

The piano pumps nicely -- one can get lots of expression out of it,
and the owner knows it may not keep working for a long time, but his
elderly father will hear the piano play at Christmas and no one in
the family has heard it play for 50 years!  Not a normal thing I would
suggest doing, but the preliminary tests of the piano indicated they
should get a few years' enjoyment out of it.

Oh, Happy New Year everyone!

David Dewey