I've been having leakage issues with the clutch and countershaft covers on my '81 495 ever since I put the old girl back together.
I'm sure fellow early-eighties 350 - 495 owners experience similar, especially from that ridiculous nylon countershaft cover that flexes every time you pull the clutch in...
The sealing surface on the clutch cover is pretty narrow also - mine always leaks at least a little and I've tried everything to try and stop it, but it eventually fails.
So, I managed to track down a local guy who manufactures gaskets from scratch.
You give him the parts and he makes the gasket in whatever material is best suited to that particular application.
I'm going to get a few gaskets made in different thickness materials to try and keep my bike oil-tight.
It's possible that a run of twenty of more could be made - are there any fellow owners who'd be interested in gaskets?
I've no idea on price at this stage, but I'll keep y'all informed when I get mine sorted.