Solidstate started this discussion on here,

"Circa 64 Otis MG problem"

You can find it using the search icon.

Also Helwig Carbon Products has great information as well.

May I ask why you wish to stone your commutator?

No problems here , just wanted to know the best way. Thanks for the info

I have Turned and under cut many a Comm, both Motor and Gen. The best way I found was to remove the Brushes, install the correct size tool to hold the Stones, put a Cadillac Vac near the work, and Turn the Comm. Then under cut with the correct size rotary cutting wheel, then champher the under cut. Finish up with an eraser stone. Use De-natured alcohol to put a glaze back on the Comm. All the Stones, Jigs, tools etc; can be found at Martindale in Cleveland. They have a great catalog. I am assuming they are still in business.

I checked out that thread by Solidstate. Does anyone know what the resolution was?

Oh yes. My bad for not posting. Thanks to all for the help. Generator was configured for wrong building voltage.

Thanks, so your problem was the AC end? Good one. Was it running the wrong RPM or bogging down with a load?

Newbie here but how do you use the de-natured alcohol? Wipe the commutator with it? Thanks,

use a spray bottle while the gen is running, on idle, on inspect. let it run like that overnight.