I have rebuilt a couple of player stacks which used a gauze type mesh
under the pneumatics.  During disassembly the pneumatics popped off
nicely.  I cannot recall the make, but these stacks were factory
original and had no previous restoration.

As a side note, the mesh used was coarse and not cut for hole opening.
I seem to recall finding a loose hot glue flake caught in the mesh of
one pneumatic, possibly preventing it from traveling into the valve
area.

John Wrasse