Just wanted to update the status of this problem, just in case somebody else draws a blank with all the great suggestions and links that were provided.
It turns out that the arm that connects the throttle mechanism to the weber was slightly out of alignment - moving this back to the intended alignment solved the problem .
Indicated here [img]
https://photos.app.goo.gl/r63dAmQd2JST5zYP6[/img]
As always, I'm very much a newbie on all things mechanical and your patience and encouragement provide a huge motivation for me. I probably would have thrown in the oily rag at this point if it wasn't for your help
