I'd put a piece of tape on the lever and trim tape to match lever, then try knob on. If still loose, add more tape. A second option would be some sort of glue (??) I wouldn't use epoxy as you may NEVER get the knob off again! Bob
I thought they were just push until it fits kinda thing. They should have molded detents that match the throttle lever, but Ive not replaced one for a very long time and cant recall exactly.
On another note, is that piece orange? And is it a Deere part?
Mine is red (or at least a much darker orange). Cant say Id like that too much if thats what I got from Deere...but I like mine to remain as original as possible, and Im kind of an oddball.
Found the answer to knob color, and an answer to your question too...
My knob broke on throttle lever bought new one at jd new one is orange old one was red, checked part number on several sites and it says i got right part number but i can't get the knob on it seems to tight ,has anyone has this happen to them?