Nuts, chains and sprockets.

[BluprintZ]

I agree the O/S thread looks bad but as i mentioned in my last post, i recon the fact that the torque wrench was clicking at 90 Nm, was probably because the new nut was cutting a thread into the shaft.
I do have access to a very good engineer/welder, although whether to go arc or mig, i will have to discuss with him.
To be honest, now that i have a new chain, sprockets and the 12mm nut on, i'm inclined to let him wend the nut on, as i few on here have done...i think?
I should get a few years out of the bike if i look after the chain but to say i'm rather gutted, is an understatement, i really was happy with the bike, until this shambles unfolded.
It's probably too late to go shouting at Yamaha for a new shaft to be fitted, although i might do, just to see if they will honour the fact that they have messed up with this issus.

Thanks for all the advice guys.

G ; (