motor not starting: my bet

["Max Hall" <maxo iname com>]

I'll bet a Dunkin' Munchkin that the problem is the contact between brush
and armature. Someone else mentioned this in passing, and I think it's 
right
on.

When the brushes (which aren't literally "brushes" but conductive blocks in
a guide) wear, the springs that push them against the contact segments on
the armature are farther extended and therefore push less hard. Add to that
a little oxidation on the segments, and you have a (relatively) high
resistance interface.

(Especially if you have had poor contact to that segment: arcing will
further increase the resistance... a vicious cycle!)

Your motor guy will know how to treat this common affliction, and he'll
probably be able to see the part affected. Adjust the brush springs, polish
the contacts segments, and as my office mate used to say, "QED" (not "quod
erat demonstratum" but "QUITE EASILY DONE"!)

Good luck!

>Just to be clear;
>occasionally, when at a complete start,
>when I advance the speed selector, the
>contactors clack on, but the motor doesn't
>budge or make a peep - nada nothing.  I
>turn the speed selector off, reach down,
>rotate the motor pully slightly, then
>advance the speed selector, and it works
>fine again.  Like a dead spot or something.
>Maybe it is friction related, but I think
>its more than that.  I'm going to try locating
>a motor shop this week, in case I get in over
>my head, then I'll pull the motor and do the
>bearings and check brushes, etc.