Nitro Rush Re-Build
I do not want to discourage you from a tranny tear down, but I just wait for some gears to blow out and then rebuild as necessary. The 4 bevel/spider gears in the diff are particularly soft, I'm surprised they have not stripped already...been through 3 sets of spiders/bevels in my Rush so far. As for the clutch bell, it will eventually become too glazed over from clutch shoe residue and the clutch will not be able to grip, so what I do is take a steel brush on my dremel and lightly go over the inside of the clutch bell. then it engages real nice after that. mind you the clutch may be too far worn as well and may need replacing.