I just bought a 66 with the internal starter/ generator. everything works to put power to the starter ead where it enters the engine case. i figure it must need brushes. is there anything else i should check before i begin what i assume will be tearing the engine down and splitting the cases. when i was looking at it before i bought it we did get it to crank intermittently and weakly a few times but now ive got nothing. any help would be greatly appreciated.