Duh, someone like me, who used to use lower gears a whole lot, find I went though 2 thin first gear bushes per set of sleeve bushes. There is some controversy on how best to ream, finish or size bushes that don't come ready to fit, as their sintered porous surface is considered a vital part of their wearing longer. Burnished over ain't ideal. Take a good long look at the position of the sleeve bushes and the resting oil level, and consider how oil could get inside while those parts are loaded and spinning. Only way-time I can see oil getting inside is in top gear so some splash drain down past the thin entry spaces might occur. What would Jim do?