Yes 12s do have an oil problem at the clutch when pushed hard i.e. drags. My last 12 had a mod up the centre of the basket to correct this (like a corkscrew). I have since had a mate, blow his clutch on a 2000 12 and smashed the basket. Ended up having to get the motor stripped as metal fragments went everywhere. It also blew a hole in the side casing the size of a 50cent piece. No fruit !!
My current 12 doesnt drag because of this!!! too risky in my eyes