I was on a run a while back, and a mate sidles up next to me and says “ya know that tranny you rebuilt for me last year, well I think the main seal has failed and I'm thinking about renaming the bike the Exon Valdez. I said lets go and have a look.
I got down amongst the dirt and leaves with a light. Hmmm? there's a lot of oil hanging from the oil tank and the starter motor is never going to rust...ever.
The good news is, I cant see any oil leaking from the gearbox seal. The bad news is that I think your oil tank is cracked.

We have another run in a couple of weeks so he delivered the bike here for me to inspect and fix the pesky oil leak. Removed the oil tank and cleaned it for inspection.



Found the culprit. This picture is taken through the oil filter hole. The crack is 3/8” long and across the end of the factory weld that holds the bracket to the bottom of the oil tank.



Crack runs under this bracket. How to get this done right?