My inner gear was shredded... this did the trick
My drive train was intermittently "locking up" when I stopped pedaling. I thought it was the clutch, but it turned out to be the inner ring of the reduction gear (half of the teeth were sheared off and there were chunks of metal floating around with the clutch).
Doing this repair isn't as hard as it looks and I didn't need any special tools other than the lock-ring pliers. I cleaned up the old clutch, greased the hell out of it the parts, and reassembled the system. Works like a charm now!