Throttle lever slips out of high when running
 

Likes to slip fast down to mid range. I cannot see anywhere to tighten tension on the lever under the dash (on a 108)
Any ideas to tighten up the tension on the lever?

On my 128 there is a bolt and lock nut that holds the lever tight. I was able to tighten the nut on mine till I got it where I liked it.

My 1650 also does this. Last time I mowed I wedged an empty shotgun shell in there so it wouldn't slip back down. Also couldn't find anything in the service manual. Like DWayne's 128, my 108 has the locknut too. But on my 1650 the throttle unit is pressed together.

If they are pressed or riveted together, take it out and using a hammer and a punch on one side and something solid to back up the other side, tap it together to tighten it back up.

Just wondering if that might loosen back up over time especially on a 1650. At certain rpm's it feels like riding my harley. Could you put a small bolt through the hole and squeeze it back together with a lock nut? Anyone try that?