In response to John McClure's open question posted in MMD 030209,
I can offer the following.  The Ampico B roll drive motor has a wound
armature, which means there are brushes which form the electrical
circuit to that armature.  During normal operation, sparks can be seen
at the points where the brushes contact the commutator.  Under heavy
loads, the sparking will be more noticeable.

Unfortunately, the brush holders of this motor are made of pot metal.
The pot metal _may_ distort with age.  This causes the brushes to bind
within the holders.  If the binding becomes severe, the motor will not
maintain proper speed and will slow under the lightest loads.  The
brush holders can be fixed by filing or total replacement.  Also, the
brushes can be made smaller to afford necessary clearance within the
holders.

Dirt build up on the commutator can also cause problems.  If the build
up of dirt is extreme, the motor will appear to be weak.  During rewind
it will come to a complete stop, and the roll will not rewind by
itself. (This is not to be confused with normal rewind braking, which
stops the roll periodically to tighten the paper)

The bottom line on judging the sparking seen, is to evaluate the speed
and strength performance.  If the motor maintains an even tempo, both
during play and rewind, there is probably no problem.  The sparks
should appear as a soft, tiny area of sparks, not arching.

Concerning Robbie's comment about the governor resistance, I personally
think he has it backwards.  The resistance is there to smooth out the
performance of the governor.  Any reduction in point sparking is only
a secondary function as the points will last a lifetime without any
resistance at all.  As I have stated here before, it is very common to
find the governor resistor burned out.  Still, the roll motor works
beautifully, but it is just a bit noisy.  Slight pitting of the points
is normal.  Heavy point burning is very rare.

Unfortunately, many of the MMD archived articles on the Ampico B are
absolutely incorrect.  While there are many correct insights into the
Ampico B, the bad stuff is thoroughly intertwined, thus corrupting the
archive.  This of course should be anticipated, since contributions
come from many sources and cannot be screened.

 [ Ye editor does not attempt to verify statements by the authors,
 [ as print journals often do.  MMDigest is simply a discussion forum,
 [ not a guaranteed source of truth.  Verification ("sanity check")
 [ is left to the reader.  -- Robbie

Any reader seeking help on this system should reference multiple
sources to confirm the accuracy of the archives.   The "Service Manual
1929" for "The Ampico" is the best source of information about the
operation of this wonderful mechanism.  Also, Dave Saul has published
a rebuilding manual that is excellent.

If the motor does require service, it can be done be any of several
experienced technicians at a small expense.

Bob Taylor