Candy:
Try screwing the bolt in. Did you try the stop lever experiment? Can you get it to idle smooth at any rpm. I would still suspect the rack dampener if it does smooth out at some point. Mine would not idle smooth until I changed the dampener. Unless you have a new one to compare to it is hard to tell by just pushing in the spring. It appears to be critical if the spring has gotten weak. Keep trying I doubt if it is serious.
Cheers and Merry Christmas.
