
After a little looking around, I figured out that it belonged to the upper assembly on the CD drive:

I cannot figure out HOW this part broke off because I cannot figure out how it fit in there in the first place: The teeth on the broken piece show no indentions that would all it to clasp into the holes inside that washer. It also shows no signs of the plastic being broken or snapped. It's one solid piece.
So if anyone is familiar with this problem, is it something I can fix?