G1 starter/generator is too weak to turn the engine over

[springwood_cruisin']

Hey Folks! The starter/generator on my 1983 G1 seems to be too weak to turn the engine over. When I got her out of storage this spring and I pushed the pedal it only turned about once every 3 or 4 seconds. After 30 seconds or so, it would stop turning over. I read through the stickies (Everything G1, So your Yami won't turn over, and G1 starter/generator test) and diagnosed a bad positive wire running to the s/g (direct from battery). When I tried to remove it, the stud on the s/g broke off. Apparently is was pretty corroded. Can these be replaced? Luckily there was just enough thread left to put a nut on. This allowed me to attach a new cable but its a temp fix. With the new cable, the s/g spun fine in both directions on the work bench. When I reinstalled it, the s/g seemed to turn a little bit better, once every 2 or 3 second but still not fast enough to turn the engine over. Battery was new in the fall and fully charged when testing. Brushes inside the s/g are still taller than the brackets and the inside of the s/g looks good through the peep holes. Any advice on what to try next and how to replace that stud on the s/g would be amazing.
Thanks!

[springwood_cruisin']

An update...I pulled the starter/generator and opened it up. I confirmed the brushes still have plenty of life left. I took the opportunity to clean up the armature while I had it open. There was some build up on the riding surface. After putting it back together and testing it on the bench, it appeared to be turning faster than before the cleaning. When I installed it in the cart again, it was still to weak to turn the engine over. It only cranks once every ~5 seconds. With the belt loosened, the fly wheel spins freely.
Another odd thing occurred today as well. Twice, when I lifted off the gas pedal after testing for 30 seconds or so, the engine sounded like it fired for a split second. I then saw some wisps of exhaust coming out of the transition piece between the engine and the muffler. I felt around and nothing was hot but the wisps continued for several minutes even after I turned the cart off and disconnected the battery and spark plug.
Thanks again...

[Lochlin]

A couple of things. First, regarding your broken stud, those are repairable. Here is a link to get you started:

http://www.buggiesgonewild.com/showthread.php?t=114626

Regarding your weak generator. This sounds simple but I would try a new generator belt and make sure it's nice and snug. A lot of times, the starter is actually spinning fine but the generator belt is too worn / loose for the generator pulley to grab it and spin it well. It will grab here and there and give you a weak revolution or two making it seem like the generator is weak. In actuality, the belt is the problem.