First I disconnected the cable at the carb and it was free to move but I added a bit of grease at each end anyway, checked carb that was free to move but added a little light oil anyway, then I thought must be the linkage underneath so I sprayed some oil on it.
None of these fixed it.
Scratched my head for a while then the penny dropped, only one thing left to check.....
It's only lasted 200,000 miles

