Neil NICOLAO said:
I have had the machine for many years, the problem has slowly got worse over time. There are no problems selecting other gears. I have pulled the clutch apart, however it was all ok.
Then I suppose we must assume this is a general wear problem, and the only way to really check is to strip the box?
One thing that could be worth checking, after removing the outer gearbox cover, does the selector quadrant look as if it has come into contact with the top of the inner cover slot? As that could stop the selector mechanism from fully selecting top gear?
If so, then the inner cover can be removed and the slot filed to give more clearance, BUT that may only cure the symptom rather than the cause which could be wear in the selector mechanism = selector forks, camplate tracks, camplate spindle and bush, quadrant spindle/bush, ratchet mechanism, etc....etc...