Thanks for the information about the Tinnerman nuts (learned something new). I got the motor apart. There was no way to give the bolt a good wack from the nut end, and I broke the Tinnerman nut trying to pry the prongs up. But I was able to get the motor apart, so now I can take care of the wiring and clean up the motor.
There is a fairly wide and deep grove in the existing double threaded rod, so I might have to replace it (maybe with a threaded rod).
Your response was very helpful, Thanks.
Tammy