Referring to a drawing provided by Bruce Hatton at Bailey's, I took my carb apart to clean any possible fuel varnish out of my jets. Though they appeared to be clean, I soaked them in Wynns carb cleaner for about three hours (overkill perhaps, but I had no idea how long a "good length of time" was). I sprayed all other parts and let them drip dry.
Opinions differ about whether you should EVER stick anything in a carb jet, but on Bruce's advice I used a fine strand of brass taken from a cheap BBQ brush, bought for the purpose at a hardware shop. (I pulled the strands out with pliers and now have a supply in a 35mm film pot). The thing about brass is that it is a soft metal, so ought not to scratch the surface of the jets, while still being useful to remove any stubborn deposits or flecks. The brush strands are zig-zaggy, which makes them a tiny bit more abrasive. I did this with great care.
When everything seemed clean (time will tell), I dried everything completely with compressed air, which I also powered through the jets to make sure there was nothing at all left in them, then reassembled the carburetter.