Hi Greg
Thanks for that, I certainly did, I twiddled everything!
Yesterday I untwiddled and reset everything to factory settings, also installing a rubber O ring between the carb and the inlet manifold as that too was slack and obviously would have been drawing air in. Since restarting it it does tick over much better but still isn’t consistent, it still stays a little too high when revved – so I’ll have another look at the tickover screw, and, it tends to die off once it starts warming up, any ideas on that one?