Although I was an employee of Player Piano Co. for a number of years,
I did not assemble or repair their roll frames.  I was building and
selling my own roll frames based on the George Cooper design, which
mostly had 12-volt DC motors and precise electronic tempo controls.
The early ones had 3-step pulleys and a rubber belt drive.  Having
said that, here is my response to a question from Herb Lindahl:

  "I have purchased many PPCo spoolframes and others over the years.
  I am attempting to repair an "A" roll frame from Player Piano Company
  from the mid-'seventies.  My problem is the speed control; when in
  play mode it is not constant.  It will sometimes slow down or speed
  up without warning.  About ten years ago I was able to replace the
  capacitor, motor and potentiometer and all worked well for several
  years.  Could you advise a possible repair for this roll frame?"

The type of speed control used in it not precise or reliable. It uses
magnetic braking action within the motor to lower the speed.  Changes
in the tension of the paper or any other mechanical drag will also
change the speed.  Make sure that nothing is binding, and if necessary
change the rheostat and rectifier that produce the D.C. braking
voltage.

The only other cure (neither easy nor cheap) is to replace the 120 VAC
play motor with a 12 VDC motor and electronic speed control device,
that produces variable 5 to 12 volts DC that is regulated.

Gordon Ramsey
Wichita, Kansas