Hi Okidoke

Being a tecumseh, I would wager that the throttle shaft is sticking from years of dirt and grease. Spray it with something like wd40 to loosen it up, then a bit of silicone spray to lube it but not attract dirt.

You should just be able to flick it back and forth with your finger. It should not be at all stiff. You may have to take the air filter housing off on this model to get to it easily

This thread may also help you
https://www.outdoorking-forum.com.au/forum/ubbthreads.php?ubb=showflat&Number=52624