Gearbox tolerances

[sparrow.2]

Was helping two mates last weekend who were having trouble with idler gears only lasting about 3 or 4 runs tops. After having a closer look we found that the stubs on which the idlers bearings run were a tiny bit too small. This allowed the idlers to move and mesh badly causing failure fairly quickly. We fixed it by pushing the bearings on through a little piece of a ziploc bag, which tightened everything up and quietened the gearbox down a lot and seems to have sorted the wear.

Just wondering if anyone else had been having trouble with the gearbox. This was on the B4.1 version of the conversion.