My first choice would be to recover the pneumatics with a good pneumatic
cloth.  This I purchased from Player Piano Company.

The question of good cloth brings up a lot of questions.  The cloth that
I first ordered from PPC was excellent.  The second order from PPC was
completely different cloth which was so stiff it was barely usable on an
air motor! I could not use it on striking pneumatics at all!

Polylon has it's problems too.  First it must be glued with special glue
which is very hard to remove the next time around.  Then of course there
are different grades of Polylon too.  Some reliable, some not so good.

It is a gamble, I guess.  I have had some good luck with Polylon obtained
from Schaff piano supply.  It is ready-cut in large rolls, and one only
needs to cut the proper length, build a form to keep the proper span, and
cover away, trimming off the excess edge.

Bruce Clark