Hello, The pumping unit on one of my Classic player pianos is in
pristine condition -- hardly used because it doesn't produce a lick
of vacuum. The bellows cloth, I've heard, was part of a batch that
Classic belatedly found to be too porous. The exterior valves operate
well; my guess is that the interior valves are okay also. When the
pumping unit from my other Classic is installed, the piano plays fine.
Before I tear off all that good-looking cloth and recover the bellows,
I was wondering whether there is a flexible sealer I could coat the
exterior of the cloth with to decrease its porosity, and save myself
a big job. Or is this just wishful thinking?