If you can find an old generator shop around, that is the kind that has hundreds of old generators laying around and he uses a probe with a 110 volt light bulb to test continuity and use a 6 volt battery to solder with, they can find your problem, because they have been dealing with these sort of things for 50 years. Another good sign to look for is a place that works on old farm tractors and construction equipment. We have several thousand dollars worth of test equipment in our shop for our over the road trucks, but I use the old techniques on my old 50's toys. If I can't figure it our, I go to an old generator shop about 30 miles from here.