I've discovered that my mighty WM20 has a slipping clutch, so off with the primary cover and that bowler hat thingy, to find oil dripping out..!
Reading through the 'How to fix it' book, I see there's mention of 2 gaskets, one is a paper one, that sits underneath that Bowler Hat thingy, and there's another one, a Cork one, but I can't see where that would go..? And of course, there wasn't one in there when I took it all to bits, so my question to the panel is, where does this cork gasket go..?
If anyone has a photo even better..
The cork 'gasket' is in fact a cork tube which is fitted inside the back of the clutch sleeve before that part is fitted to the main shaft..
There is also a felt seal on the clutch pushrod and another felt that fits over the main shaft and against the end of the sleeve gear..
Saying all that though I never fit any of them and have done tens of thousands of miles like that without problems....
I find the oil usually gets in under the clutch bowl if it gets in at all...
Make sure the rim of the clutch bowl where it sits against the sprocket is flat...they frequently become distorted from years of having the screws tightened..
Spend some time dressing the surface if it isn't flat...Then fit a new gasket with some silicone sealant...that should do it...
If the fibre plates are contaminated with oil, boil them in a strong water/detergent mix for 10 minutes or so and then leave them in a warm environment until they are COMPLETELY dry..Rebuild the clutch as normal....Ian
Hi Shaun
I've got a few diagrams of the clutch / gearbox gubbins which helped me work out where everything goes. If you drop me an email I'll send them to you.
They were on my website but I closed it down because some git started infecting it with viruses and I couldn't be arsed with constantly cleaning it up. 
Cheers
Pete
email (option): petercomley@web.de
Thanks lads, I found that cork tube jobbie, it was hiding..! But another question has popped up, the shaft that's poking out of the gearbox, seems to have a felt washer wrapped around it, should this not be an Oil Seal..?
Peter, E-Mail is on it's way thanks..
I've decided to throw the fibre rings from the clutch away, they seem to be a tad thin, and being soaked in oil isn't helping, although I DID clean them up. Best to start with all NEW stuff I feel, give the bike a chance, it's got a LOT of work to do in 2014...
Fibre clutch plates are .093" thick when new....Ian
Well that's it then Ian, mine are about .080" I feel a trip up to see Les at Russells coming on, glad I'm not busy on Friday..