I have just replaced the reverse gear in my gearbox (3 rib Type 2 Bus 002 ) and after putting it a old gearbox (with windows cut out for inspection) to make sure all gears are working.
I put it all back together every gear works fine except revers gear which pops out. Pulled it apart again and can see the reverse gear was not going all the way in. when i try putting it in to reverse gear while apart and in the jig it goes in perfect.