Geez, I didn't know that player pianos used rubber friction drive
parts. These wretched items are, of course, a specialty of consumer
audio equipment, with which I dealt for many years.
The best old source was the Projector-Recorder Belt Company, of
Whitewater, Wisconsin, and many a belt and wheel did Kinsler Hi-Fi
Service buy from them. They became PRB, then something else, and now,
combined with the other belt company EVG, they're at
which is important because they _used_ to make and restore old idler
wheels and also build custom belts for weird machines. I don't know if
they still do that. Player piano stuff may be a bit on the large size
for them, but perhaps not. Anyway, their catalogs are there, and you
can perhaps find something that'll fit.
Lancaster, Ohio, USA
[ -- Robbie