Thanks for the tips guys - I used the talc method to trace a cylinder head leak a couple of months ago, so I know it can be pretty effective
However, in this case, the oil is coming from the little slot between the bottom of the swingarm and the bottom lip of the gearbox casing - impossible to get talc on the back face of the gearbox (and them impossible to see it without removing the swingarm!).
So, the swing arm's got to come out. To be honest, I'm ok with it - as the bike's done 34k, it'll be a good chance to check the paralever and swingarm bearings. I just need to research a good method for re-torquing the bearing pre-load / locknuts without the special tool.
I'm sure I read something about locktiting the pre-load screw and using a marker pen to mark its position once you've torqued it (and then possibly leaving it for the locktite to go off?) before attacking the locknut. But I'm bu**ered if I can find it (and I can't remember if I read it on here or ADV).
cheers
Matt
ye have just about got it, but when torquing the pivot bolt up , move yer swing arm up and down so to get the correct torque setting, and if ye mark yer locking nut ye can see if its moved or not...
best to get a mate to help..
look at mine n diggers thread gearbox removal,

ugg
. I guess this explains how oil is leaking out of the output seal without running down the swingarm. No idea how long its been like this - hopefully the drive shaft UJ hasn't suffered.. I'm not surprised it's adrift - it looks like it'll be a right sod to get this boot on properly.