OK so it doesn't look like the diaphragms - now I notice that it's only firing on one cylinder - trouble is, that might be because I didn't put the diaphragm back in properly, or it may have always been doing that - why didn't I check the exhaust pipes with my hand before I started fiddling? Why indeed, and this is why I should stay well clear of DIY bike repairs.
On a lighter and perhaps more useful note, Halfords are selling a 58 piece Ratchet screwdriver set including Torx bits for 15 quid, reduced at the moment.
Oh well, off to the £50 an hour garage it goes any recommendations for Brighton based mechanics?
Cheers
Scardo