Hi Blue,
You bet it's frustrating. I'm going to try the three long thin bolts tomorrow and see if I can see the circlip under the ally plate. I must admit that I think you are correct in saying that the internal driveshaft type arrangement wouldn't be the go. I must admit I too have done plenty of motor rebuilding in cars but this magneto stuff is something I haven't done much on at all except for Briggs engines and their points.
I'll let you know the result asap.
Once again thanks for your moral support.
Cheers,
BB