stu45,
If you undo the nut until it is flush with the bolt end and then tap it on the end it will release from the crankshaft. The bolt shaft is half moon so when you tighten the nut up it locks onto the engine shaft.
Note the bolt does not come out until you remove the clutch housing from the engine shaft.
If you download the parts list from the parts list and manuals area you will see what I am talking about.
Hi stu45, the above quote should explain for you how it works, you will see it more clearly when you remove the engine. If you have to use "gentle persuasion" to get the clutch assy to slide off the engine shaft, just go easy as the alloy
can fracture.(I've seen it happen)
Best of luck with it,
