Ok,
I had time to work on the tractor over the long weekend. I found I had voltage at the motor terminals but the E20 motor was not spinning consistently. This made me think the motor was the problem. I temporarily set up an E-12 motor on the floor and swapped over the wiring. The E12 ran fine with no load.
I pulled the motor out and did some testing tonight. I did a 4 point resistance test. Years ago I got approx. .07 ohms. Tonight I got .08 ohms in most shaft positions but as high as .58 in one position. I think that is where the pulsing came from and the failure to start sometimes. The commutator is grooved. One brush feels good. The other does not feel like it slides in and out smoothly. I believe I have a new set of brushes on the shelf.
Any tips for what to look for in the brush holder and how it should feel? Is it possible to find a replacement brush holder? I can turn the commutator on my lathe but how critical is it to undercut the commutator?
If I have problems repairing, any recommendations for a replacement motor such as a Motenergy ME0909/1906?
Thanks,
Rob Brockway