Thanks for all the great responses guys. I have split the cases, have a nice crank and 2 cleaned up case halves on the bench.
Turns out the centre gasket looked a little dodgy.... it broke up easily right behind the crank (where the gasket is only about 5mm wide mind you!!!) . It was old and very brittle, so I am hoping that was where the oil was seeping through.
Thanks for the tip bikeaholic, but the PE doesn't have those inserts, it appears to be a solid mill. One thing that was interesting though and looks like a modification (perhaps a "Z" model mod??) is that there is a milled out area inside the gearbox area directly in front of the lay shaft... almost looks like they modded the Z model to have a larger gear ? (I have no idea which gear it is, but it's closest to the clutch assy). This "milled out" mod makes the wall thickness even less between the rear of the crank and the gearbox area. Probably doesn't really help the oil seeping through issue! I took sone pics of it last night and can up them when I get a chance.
Anyway... it will be getting new main bearings and a nice fresh centre gasket tonight..... fingers crossed!
