I know this is a long shot, but does anyone have an armature to one of these? One to an older model may work. I will pay well, I have wanted one of these for a long time, and the one I got has a big crater in the commutator.
It looks strikingly similar to a Cadillac armature. Now that's probably a long shot. It could be repaired, rather painstakingly. It would need to be rewound - most likely - and they do sell commutators by themselves. aliexpress, probably.