I change my front sprocket and I now have an oil leak which I presumed was from my pushrod oil seal as this is what people had told me was a common thing. I changed the seal and gasket. Still leaking. I changed the seal, pushrod and gasket. Leaking worse. 100 mile ride and two drips within a minute of parking up and light film on centre stand. I changed the seal for a double lipped seal, new gasket. BUT LOOK WHAT I NOTICED . . . . . . . I think this is the culprit. See the two pics.
This is what Alan Milliyard uses. . . and he's a best of an engineer https://www.permatex.eu/product/supra-grey-gasket-maker/ Permatex Supra Grey Gasket Maker 80ml Available world wide. I got mine off eBay for £8