Hi Pleiades,

Answers to your questions -
1. I am turning the motor over by hand at magneto nut with spanner, yes its in neutral, Still jams even with clutch pulled in.
First thing I looked at after this occurred was clutch boss nut and it was tight.
Was just turning it over now and the crank turning about 340-350 degrees, just not completing a full revolution.

2 Haven't had any problems with false neutrals, jumping out of gear or any transmission hassles.

3. Yes it does say 'Yamaha Motor Italia S.p.A'