Thanks to all those who have posted tips etc, I ahve just rebuilt my gearbox and found that top gear would not engage. I ahd followed th advice in the manual and old brits site but was one tooth out on the cam plate and quandrant. So, I reoved the gear cluster and loosely assembled the gearbox with the quadrant and camplate along with the plunger, and checked the gear selection so that the quadrant arm did not foul the inner cover aperture.
Another, thing that I found was that the mainsahft would tighten off even with the inner over fully bolted down, this found to be the kickstart shft not correctly locating in first gear. Lokking at it it would appaer that it would be impossible to get the inner cover on if that was the case, but easily rectified by placing the kickshaft shaft in the first gear and placing the inner cover over it, then operate kick start shaft so that it locates properly with the spring hole facing aft.
