Yes, I read elsewhere in the forums that these pesky carbs can be prone to "going off" when stood. That's frustrating (particularly when the bike will no doubt be used on the rare sunny days we have.
I've found a detailed carb stripping guide (will check if it's the same you mentioned Ash) & will consider doing the full job (at least I'll be able to make them look good even if they prove tempremental). I've also read of a contact in Holland (I'm blanking on his name atm but have written it down at work - Van Der G... something) who sounds like he does a cracking job at fettling them which could be a fall back option. I like the idea of the hex headed screws! I've done the same to the engine with SS replacements (the old ones on there seem to be made of brown cheese). Is there any resource that specs th various sizes, thread types etc. of screws, nuts & bolts throughout the bike that will help in finding, as well as replacing/swapping, them as the bike slowly goes back together?