Thanks gentlemen, as ever a mine of useful information. It is good to know Ian that a cheap Chinese carb wouldn't be a complete waste of money, but taking the advice of Michael and Bill I will be trying some fresh E5 first.
I am sure the MM wants to run, now more so than ever, but like our long-case clock once one tiny thing is disturbed lots of other things seem to go out of adjustment. I am pretty sure that if I get the motor running then I can work through the other things methodically and have the bike ready for spring. With Justin our clock (Justin Time - sorry) we wait for our friend Trev to pop over as he is an horologist and knows what to tweak to get it running again, sadly he knows nothing about thumpers. But you lot do!
Ian