I believe your theory is right on Stuart.
The first thing to do is find out if the problem is the gen. or reg. Remove the wire from the field term. on the reg. & ground it. Start the engine & the charge ind. should go way over on charge. Obviously don,t run it very long like this. If it doesn,t you will need to repair the gen. You shouldn,t have to adjust the gaps on the reg. but the voltage & current can be if you read up on it & are very careful.
