I knew someone who destroyed his Morris Minor gearbox by neglecting to put a bush in. On the BMC A series I can't remember whether it goes in the flywheel or directly into the crank.
Back in the days when we had our Series 2 forward control we acquired some billets of phosphor bronze from a stall at Beaulieu autojumble. Combined with a small vintage Myford lathe this was very useful. We made the bush we've just been talking about, plus a larger top hat shaped bush that formed part of the clutch release mechanism, which apparently you couldn't buy any longer.
It's funny stuff to turn. It starts out peeling away like any other non-ferrous work piece, then all of a sudden decides it's a bearing and won't play any more, and the lathe starts vibrating and the tool starts smoking.