I thought the main leak I had was coming from the crankcase join between where the engine bolts to the box and I was expecting to see a shed load of oil come out from that void when I unbolted the box... Nothing, nice n dry inside... But there was a lot of oil all down the back of the engine behind the magneto, over the cam area, around the outside of the square gear box flange, on the top cylinder barrel fin, the cylinder head fins, and the rocker box gasket is a total mess of splits and voids. I've already got some copper rocker gaskets to try (thanks TT John). I'm thinking that maybe all or most of the leaks I thought I had might be attributed to this. It was dropping a lot of oil, and it was blowing/running/dripping everywhere making it very difficult to trace.
Onwards.
Jase