Jim Moore asked if it was composite or leather. Mine was a red rubber
(iron oxide filled natural rubber) ordinary v-belt with a cord backing.
The thing had decals on it saying "NRA-- We Do Our Part". I suppose I
should have kept it when I got a new one in 1986, as it was 50 years
old then. The piano was dated June 1935 on the pump casting.  It still
has many original rubber parts.

Karl Petersen
Rushville, Illinois (really)