I've got a 1949 Allis-Chalmers B that has some sort of a short in the ground. It ran fine all summer until one day late fall it just wouldn't kick the starter. Tried jumping to both posts on the battery with no result. So then I just connected negative jumper to the starter switch screw and touched the positive to the back of the starter and it fired up fine (so I know the starter is good).
I've read about the grounding issues that can occur where the starter sides into the housing, so I've wire brushed that area - as well as the screw that keeps the starter in place.
I've bought new switches for both sides of the switchbox, and an ammeter and traced the wires that go out to the generator, battery and magneto. I've also checked from the negative battery post to the starter switch, as well as from the positive (ground) post to the steering wheel post. When I check from ground post of battery to the starter housing (or the screw in the bell housing) I get nothing.
This is a straight up textbook 6V system with generator and magneto. I keep going around and around trying to find out what's wrong... Any ideas of what I might be missing or what is wrong?