Did the job last week based on this thread.
The garter spring was in 3 parts, some of the excentric bearings were scorned with a few of them having bits broken off & stuck on the magnetised flywheel as well as part of one of the stator's ceramic caps broken off but the rest of the stuff in there was Ok.
I hand filed/sanded the excentric bearings back into reasonable shape, installed an SKF 19993 oil seal garter spring, lightly sanded the starter gear's contact point with the sprag clutch & sealed the stator's broken ceramic cap with a dab of epoxy.
Put the whole thing back together, crossed my fingers & went for the button &...... Bingo, the stator now works like a charm for $9 instead of $100!
About the damaged excentric bearings,
Some where badly scorned on the sides preventing free movement in the assembly & some where pinching the garter spring in their slots; a couple of hours of carefull hand work brought them back to a useful life ...to my surprise, I must say!
This ''restrictive movement'' of the assembly might be the cause of some of the unsuccessfull attempts at this repair & the garter spring certainly won't last for long if it's being pinch by some of the excentric bearings; carefull inspection & correction of each & every parts of the sprag clutch assembly should be done while replacing the garter spring & putting the whole thing back in the bike.
When installing the sprag clutch back into the flywheel, you need to push it in deep enough that it will kind of snap into place (Magnectic click, I think); it may look to be in deep enough but it might not be the case & could move out of the flywheel to do some major damage.
I have access to my dealer's 640's flywheel flywheel puller &, with this tool, the garter spring replacement will be done as regular preventive maintenance from now on ...even if I, now, have my kicking technique down to an art form!
It's an easy fix & takes no more than 30 minutes to do so if the excentric bearings are intact!
You the Man, Losiu!
Thanks to all whom have added to this thread; do keep it up guys!