I recently brought a 25-year-old Universal player piano into my shop
for repairs.  It was playing weak and missing many notes.  John Omiatek
over at QRS warned me I might encounter bad Perflex pouches.  To my
surprise when I opened the  valve assembly and inspected things it
wasn't the pouches.  In fact, the pouches -- made of a "Perflex-like
material", as John called it -- were in great shape.

They were strong and flexible. I inflated them with a tube in my mouth;
I vigorously poked at them.  They were in such great shape, I didn't
see any benefit to replacing them.  This went against everything I ever
experienced and was told about Perflex.

It turns out, the real problem was, the material had come loose from
the pneumatic.  When I told John Omiatek what I discovered he asked me
if it was a yellowish-green material.  I said yes.  John said they did
have a problem with that plastic cloth.  This cloth exuded a gooey
substance similar to Tygon tubing.  The cloths adhesive even became
gooey from the plasticizer or whatever the heck was going on.

All the pneumatic cloth easily pealed off. I used naphtha to clean up
the gooey mess left behind and scuffed each pneumatic a little with
sandpaper.  I put rubber-coated cloth material on using PVC-e adhesive.
The valves were great also, very airtight.

Bill Maguire