utilitarian wrote:
OK. Update. I ran the motor with the belt off. Got the same
noise. I noticed the stem which turns the belt was a bit loose in the
motor. Or maybe the whole motor assembly was moving around in it's
mooring. Don't remember at this point. I turned it and it spun
freely until it stopped. Turned it harder and it got over the
resistance, and kept moving, but then stopped again. This time I could
not get it to turn in either direction. Plugged it in for just an
instant and the motor just buzzed, but the stem did not revolve. I
only let it buzz for a fraction of a second. So now ther motor is
stuck, apparently. I can see two fans, one on either side of the
motor. One is a big plastic fan and one is a smaller metal fan. The
plastic fan had a nut loosely holding it on. Maybe it was letting the
plastic fan flop around and make the noise. I tightened up the nut.
The nut tightened in the opposite direction of a normal nut,
interestingly.

From looking into the fans, I can't see any debris in there that would
interfere, Maybe one of the metal blades on the metal fan is bent, and
rubbing.

I fear that I turned the motor in the wrong direction (backwards)
(can't remember which direction) and screwed up the brushes. Is that
possible? I can force the metal fan to move by prying on it with a
screwdriver.

I can tell now that the stem should be turned counterclockwise, to
make the beater roller turn in the correct direction.


Sound like the bearings are shot. Time for a new motor if you can find a
replacement.