Hey Cal, thanks for your reply. From your reply the solenoid is in correct orientation I presume.
The rectifier checked out fine on the multimeter, but close examination shows up as very stained and old looking (not surprising I suppose), I'm worried about cleaning it too much in case I damage it.
I have 3 rectifiers but only one is good. Let me know the price, a spare would be good.
I'm also concerned about the old connectors and wonder if I'd be better off replacing all the wiring on the plate.