[ Ref. 150224 MMDigest, Sponge Neoprene for Valve Seats

It's well known that the neoprene valve facings leak on newer Aeolian
players with plastic valve blocks.  The neoprene gets harder with
age and they can warp.  If you place your finger to cover the top hole
of the plastic valve block, the pneumatic will often close, indicating
valve leakage.

When these newer Aeolian players get hard to pedal or the vacuum motor
cannot overcome leakage, the vast majority of the problem is still
going to be the striker pneumatics, in the majority of instances.  Unless
you hear air badly leaking from the valves with your stethoscope, the
pneumatics are mostly the issue.

I test how stiff the pneumatics are and poke my finger into the highest
and lowest pneumatics to see how strong the cotton mesh is.  I close
the pneumatics and listen for a "crunching sound" indicating the rubber
coating is pretty much "done".  If I hear that "crunching sound," air
can now leak through these pneumatics as if there were _never_ any
rubberized coating.

My point is, modern Aeolian players can tolerate the small amount of
leakage at the neoprene valve facing.

Bill Maguire