Toro starting trouble

Hi, I have a Toro Personal Pace (model 20372) that is a great mower; the problem is that I’m a bad owner and forced it to cut calf-high grass for two years. At some point I figured out that I could mess with a little arm on the side of the mower in order to increase power (via increased gas flow?). For a while I used a twisty-tie to regulate this, but over time the mower began to die occasionally, then more and more often. Now the only way I can start it is if I bleed some gas out through the carb (I think that’s what I’m doing, anyway), and it dies pretty quickly.
One thing that may be important: the arm I was messing with had a pin of some sort (looked like a bobby pin) that got lost. I tried to rig something in its place, but never got it right. Photo attached.
I enjoy tinkering with stuff, so if this is a fix that a competent homeowner could do, I’d be grateful for any advice!
Thanks!
Annie =)
P.S. One other question: Sometimes bugs get into the gas tank. I should probably fish them out, huh? (Ew…)