OK, here with the post-game wrap-up...
I took down the head unit and opened it up.
The gears look fine; no significant wear or missing sections. (Last time I had to replace the gears there was a large amount of plastic "snow flakes" from the stripped gears inside the housing.) So...not seized gears. I was hoping this was the case as Sears has the parts and the set is $25. But, no such luck for me...
There is a shaft off the back of the moter and a resolver off of the other end of the motor shaft. Both can be used to freely spin the motor. So...not frozen motor bearings.
When I spin the motor, the limit switch shafts also move appropriately, so that's not it either.
Anyway, end of troubleshooting for me. Bad capacitor? Bad circuit board? Bad motor windings/bushings/rotors/???
No idea. But it's not worth my time at this point.
However, maybe someday, someone using the search function may someday find this helpful!
Stay tuned for a new thread on selecting a new unit.
Iowa mrfixit; Thanks for the link; I am definately considering it. Your advice welcom in new thread tomorrow!