Ok I've removed and dismantled the wiper motor. As per earlier suggestions, the motor is a remanufavtured part, previous owner probably had a faulty motor in the seventies and had it replaced, hence colour change and spliced wiring.
I've decided to keep existing motor rather than replace as it appears on the surface to be period correct, and you know what, it's part of the car's history so if the original part failed I think the replacement part has earned its keep
I'm going to repaint the main body today with eastwoods under hood black paint with undercoat first.
Does anyone know what colour the end part should be ? I would like to keep it reasonably factory correct, looks like it's a chromium plated covered lid ?
Also, and am in 2 minds, should I replace the spliced wiring ? Can you buy factory correct wiring or after market only ?
I'll post pics shortly. Anyone got pics of internal workings as the springs have come out. Thanks