Three Speed Gearbox 2nd Gear Rattle

[PeterWHills]

Gearbox Rattle - Some might think I might be the world’s most experienced Morris 3 Speed Box renovator but read on:

Recently I renovated my gearbox with new phosphor bronze bushes and best gear clusters I could find. Also new layshafts amongst other bits fitted. When on the road, in 2nd Gear, a loud rattle emanates but then at say 15mph it goes away (not really a resonance). In first gear we all recognise the usual whine then in top gear, almost silent.

In January I plan to remove the gearbox yet again. My current thinking is that the 1st and 2nd Cluster thrust washer thickness could be the cause. Mine were fitted with precision and about equal thickness each side of the 1st and 2nd Gears. I am wondering whether one thrust washer should be thicker than the other? It is impossible to determine if they could slightly touch because the gear lever lid has to be in place (this be a red herring)?

Alternatively could the Gear Selector Arms position the Second rattle closer to the First Gear due to a worn select. Perhaps at a higher speed the gear repositions itself?

How do other 3 Speed Minors sound when in sustained second gear up a hill?

I would appreciate your thoughts and experience.