Does anyone have any tips for getting the gear box running smooth? I'm currently getting clunking when changing into 2nd, only when cold. I've changes the gearbox oil twice in the hope that that would correct it but no change. The clutch is good and adjusted well. Not sure what to try next, don't fancy changing the gearbox.

Unfortunately, the second gear synchronisers are often the ones that wear most/first.

My best suggestion is to try rev-matching the engine to the road-speed whilst you're changing gear.

Give the synchro longer to work, so there's a definite 1st - pause - 2nd. Hurrying them doesn't help, and the 2nd synchro is weak on these boxes; I broke a LOT until I started giving the rally car an easier time, and since doing so I've not broken one. If it still grinds when you do that, then if you want to get rid of it you have two options - a new gearbox or rebuilding the one you have...