http://board.marlincrawler.com/index.php?topic=78097.msg918917#msg918917
here pics of what im talking about.. they were missing (in these pics) on my case with m.c 4.7s. they were also missing in 5 other wheeling buddies rigs where i live. might not even be your issue at all but worth a check.
absolutely NONE of the snap rings or detent balls or anything like that were missing or slopping around. There is no damage anywhere else in the case but the teeth that broke off the MC gears. I do have quite a bit of experiance building dual case setups, so im familiar with all of the things that could go wrong during the assembly process.