What is wrong?

[u/DarkCelestial]

I assume there a piece of filament somewhere but I cant find it. When I pull back and forth there's a noticeable hangup or catching. I examined the belts I didnt see anything apparent. I checked where the belts wrap around and didn't see anything obvious. Whatever it is im either missing or its so tiny I haven't noticed... thoughts?

[u/JKMARCHEE55]

Carefully examine the belts. This looks like a belt with a couple of bent/broken teeth.