Took off the primary cover and engine oil came out.....looks like the engine is pressurising the crankcase. The Combat has no PCV fitted just a hose to the oil tank. So...... fitted a Yamaha type one I got off the net. The clutch looks to need about 30-50 thou of shim to lift the clutch pack up for the diaphragm to work properly. I can see scope creep setting in for what was just an oil change.