I had a gear that was not properly hardened in a Suzuki Esteem, and the tranny ate itself. Under warranty, so had the dealer fix it. They did a crappy job cleaning it out, and within two weeks of getting it back, the input shaft seal had failed. Took it to a different dealer who could not believe how much crap was in there. He replaced the seals and all of the bearings again. It only takes a few slivers of overlooked swarf to ruin all of your hard work. Clean the shit out of everything, dissasemble everything, and flush every bearing completely. If there is still oil stuck to something, there are still bits of metal stuck to it, too.