I thought that too, but after I looked more closely, I don't think it burned.
I think that is 40 years of carbon dust from the brushes arcing and being deposited on the wires. The piece of fiber board that the brushes are mounted on was similarly coated. I could not get it off of the wires without risking removal of their insulation.
The motor does run. I partially reassembled it and tested it last night.
Warning and wisdom noted however. I will consider whether to heed it. I would not be so much worried about having to take it back apart (that's easy now that I know how). It is potentially setting my car on fire with some crappy old motor.