bushman wrote: flat out in fifth gear. I coasted to a stop and tried the kickstart,yes it was locked solid

It rolls with the clutch in, otherwise it'd have locked solid at 100 odd mph and slid to a halt unless you could click it into neutral which'd probably involve using the rear brake to remove the load from the gearbox, no one would think of that whilst skidding at 100mph.

Absolutely clutching at straws but removing the drive from the crank (and I guess you should also remove the flywheel just in case something has got in there) then trying to spin it will totally establish that the problem is inside the cases.
Plus that's all got to come off anyway.
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