Hello,  I am repairing a spool frame made by Player Piano Company
(PPCo) which was popular and sold in the 1970s and '80s.  It was
used in large numbers in build-up "O"- and "A"-roll machines.

The problem seems to be an unstable tempo control.  When first started,
the motor will barely move.  Then, when the speed potentiometer is
turned the motor goes to its highest speed and cannot be slowed down.
The electric motor was replaced two years ago because it had died.

I am really hoping to find a wiring schematic which describes the speed
control circuit.

Thank you,

Herb Lindahl
South Windsor, CT
http://www.herblindahlpianotuning.com/