I think I finally fixed it...
When I bought the 88 beater Avanti neither of the power windows worked.
I replaced the motor on the driver's side and the gear on the
passenger. In the 10 months I've had the car I've had to re-fix the
driver's window multiple times. It would work for awhile then not. I
cured some switch issues with BMW switches and relays and it worked for
awhile.
When it stopped working it would fail in the up position. One time I
thought the motor had gotten soaked in a bad rainstorm so I took it
apart let the thing dry out and tested the motor. Worked fine so I
replaced the outer window seal stuck it all back together and things
were fine...for awhile.
I tried loosening all the bolts to see if the regulator was binding,
peaked inside the door with my borescope for interference. I even
welded a tab on the end of the gear in case it was going too far and
locking at the end of its travel.
Even though the motor would bench test fine every time it was detached
from the regulator it would still lock in the up position once
assembled. I was finally able to duplicate the porblem with the
regulator out of the door and when it would lock a tap with a hammer
and it would relase and go down. No matter how I studied the regulator
I could not see anything that would cause the bind. I finally relented
and bought another motor. Installed it and things seem to be working
fine.
I just wasn't comfortable with the repair because I couldn't believe
the motor was the culprit even though the new one seems to be working
fine. I started looking at the old motor thinking I could see something
that would explain the problem and lo and behold...
I pulled the gears out a little to make it easier to see that the shaft
is not perpendicular to the base on the motor to the left. I feel
better now.
ErnieR