Hi All,  sealing bellows cloth can be a touchy subject, so let me start
by saying that the correct thing to do is replace old cloth when it's
worn out or leaking.  However, there might be any number of reasons
why a person makes the decision to seal or repair old cloth instead of
replacing it with new cloth.  A few that come to mind are insufficient
funds, a lack of knowledge or skill, and the desire to make sure that
the cloth is actually the problem.  These are all very legitimate
reasons for seeking out an alternative.

Realizing the above to be true, I started looking for alternatives
the very first time I worked on a player piano in the very early 1970s.
Back then, there was very little information available about repairing
player pianos, so I was on my own, but that didn't stop me from trying
various techniques.

It wasn't until a few years ago that I finally found a product that
actually worked.  Not only did it seal the old cloth, it actually made
it more supple than it was before I started.  I won't mention the
actual name of the product, but it's used to put a rubber coating on
the handles of hand tools.  I've created a web page that explains how
I've used the product -- http://www.player-care.com/plasti-dip.html 

For those who might decide to 'blackball' me because I would dare to
make such information available to the general public, let me say that
now I routinely use this product to troubleshoot the lower section (the
exhauster assembly) when I can see that the old cloth has already been
replaced.  As has been noted here in the MMDigest over the years, there
have been periods of time when replacement cloth failed because it was
not correctly manufactured.  And since there is no way to identify this
cloth simply by looking at it, I felt it was necessary to come up with
a way to prove to the customer and to myself that the cloth was bad
before advising that it be replaced.  However, I only started using the
product in this fashion after a customer showed me how well the product
worked on his on player.  (That's explained in the web page.)

Musically,
John A Tuttle
Player-Care.com
Brick, New Jersey, USA