I have blown out the carbie numerous times as I had suspected water in the carbie & it has driven OK for a while. Anyway, after reading a Weber diagnostic chart & looking at an overhaul kit chart & looking at a spare Weber I had, I made this amazing discovery. So, I had never been blowing out this area.
Both jets are really easy to unscrew & then I removed the idle/mixture jet. On with the compressor & a good blasting in all directions. There were numerous small drops of water coming out, especially from the LHS jet area. I did this for about 30 mins until no more drops appeared.
After re-inserting all the jets, the car idled really well for about 10 minutes but I did not have time to road test it so that will really tell me if my cleaning has solved the problem.
Here are some not very good pictures of the idle jet screws.