Final Mee-mee update: I fixed him!!

Turns out, it wasn't sync screw related, but tilt sensor and chip related! Not sure which contributed more. I'm assuming the chip. But after opening this guy up, I went in and cleaned some suspicious stains off of one of his chips, and figured that while I was at it some further cleaning and inspection wouldn't hurt. His tilt sensor was a little gunky so I'm glad I took a peek at that! I did some test runs and this guy runs better than ever, albeit a little jank still. Though, that could just be the batteries. I'm going to buy some fresh ones ASAP, but until then Mee-mee is practically functional! Thank you to everyone that offered their advice and input :D