This problem sounds like it is being caused by the automatic rewind
roll paper tightening brake (Reroll Brake).

When the roll is rewinding a pneumatic intermittently closes,
stopping the take-up spool.  This tightening brake band is located
on the left end of the take-up spool spindle, under the left panel.
Its purpose is to intermittently tighten the paper on the roll as it
rewinds.  It is effective, especially on very long playing rolls.

However, the brake band can become too tight, the valves controlling
it can become sluggish, or the brake band might become gummy and
collect dirt and apply too much braking.  The transmission also has
an adjustable clutch to prevent the electric roll drive motor from
stalling and perhaps damaging the motor.  Both adjustments are
extremely critical and if not adjusted perfectly, and _frequently,_
they will cause numerous problems.

As a young service technician starting in the 1950's, I dealt with
this annoying problem for a number of years.  I had the opportunity to
discuss the problem with men who had worked in the service department
at the Ampico factory.  They suggested the simplest (and best) solution
is to disconnect the brake band and allow the rolls to rewind loosely.
When they have rewound, gently tighten them by hand.

I'd much rather hand-tighten a roll than to have it destroyed by this
frequently malfunctioning mechanical device, or have the roll drive
motor damaged by the brake jamming and stalling the motor.

This same brake band can also the major cause of serious damage to
rolls as they rewind.  If you have experienced tearing of rolls on
rewind, on the model "B"  this can be the main cause.

I agree, this brake system might have been fine when the pianos and
roll paper were new and everything was in perfect adjustment, but many
of our treasured rolls are showing their age and are becoming quite
fragile.  Fragile rolls cannot take the stress of any reverse drag on
the take-up spool.  If you disconnect this automatic brake band, and
make certain that both ends of the take-up spool shaft are well
lubricated, both problems should be resolved.

Bruce Clark