Success as I have managed to remove rotor using the flywheel puller and hot water method. Many thanks for the advice!!! Nearly crapped myself as I wasn't expecting a crack sound when the rotor gave way and came loose. Sprag clutch appears to be held onto the back of the rotor by three star/Allen bolts. My plan is to clamp the rotor in the vice to hold it whilst I loosen of the the three bolts; I will clamp it between two bigs of wood block to protect the rotor. Can't see any obvious wear on the spring but to be honest I'm not too sure how much play would cause it to slip.

Replacement parts have now arrived courtesy of flea bay. Befor fitting though I wonder if anyone can confirm how many Allen bolts should be used to attach the clutch sprag to the rotor. There are six holes but I only have three Allen bolts. Could be that the previous owner has been tinkering and didn't replace all six bolts I guess but I thought I would ask the question in case the original design is only for three. Any info would be appreciated. Cheers

Both of my flywheels only have three bolts, so you should be good. I don't think all six holes are even there in the bearing plate or line up if they are there.






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Many thanks - will crack on then

Three holes are for the puller when required. The other three are used to attach the starter gear to the magneto flywheel.
Non electric start flywheels have only 3 holes (puller).

You're welcome.