Try checking the field coils for continuity. Remove the back plate of the generator and slip pieces of paper between the brushes and the armature, then use an ohm meter to check the resistance between the "F" terminal and the insulated brush. You should get a reading somewhere around 10-20 Ohms. It's possible a simple change of the carbon brushes will get the generator back into operation without a complete overhaul- - - -with a cost of around $10.00 and an hour or two of labor time.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!