I have an old Genie screw drive (Pro?) 9800 opener- vintage 1981 ~ 1986. Recently it stared doing something peculiar.

I go to open or close it- with the wall switch or the remote, and I can hear the motor buzz for a few moments and shut off, but it does not run. I replaced the capacitor, but that didn't solve the problem. I turned the motor by grabbing the end with the two jam nuts- it turns easily- and it will work again.

I cleaned the contacts on the interrupt mechanism with contact cleaner/lube but it still goes into "no-go" mode.

Also, everything is well lubricated, door moves easily up or down.

Any ideas? Does this motor have brushes? Yes, I know it is old, but I like to keep things working, not just throw them out and replace an otherwise good piece of equipment. I also don't want a new unit with the safety lights, and other added complications.