Harvey Roehl was asking what he should do to get his Ampico B motor
armature rewound [991111 MMDigest].
That is a common problem with that motor, by the way. I have a local
motor shop here in town that knows of a small motor shop somewhere in
California they send them to be rebuilt. You can ohm out and hum
the armatures first to see if this needs to be done. Probably you will
find someone in one of the motor repair trade journals.
The reason it happens is because of the pot metal brush holders. They
swell and grip the brush, creating a lot of heat between the brush tip
and the commutator plates, since the brushes can't make tight contact.
The constant heavy arcing finally overheats the connections and they
break. Also the heat causes the tar to soften and flow over the
segments, increasing the connection problems and heating effects.
The first thing to do in order to fix these motors is to remove them
and replace the brush holders with a machined brass set made by Robert
Streicher (as mentioned in previous articles). The next thing is to
replace the brushes, clean up the bushings and re-oil them, and clean
the motor, getting off the carbon residue and buffing up the commutator
to a degree as to remove the varnish which has been burned down. Motor
shops have armature testers for large armatures, but usually don't want
to work on anything other than industrial motors. Getting the armature
reground is expensive, but it's the only way to go.