Stumped

I’m working on an antique g’father clock. But, I’m stumped. Weights are correct—heavier on the right. It’s level. I’ve used canned air to remove dust. It's been oiled, too.

It runs anywhere from 3-5 min and then stops. Seems to miss catching the wheel about the same spot each time. 

Any suggestions?

I hold my breath at the 40 sec and 10 sec and sometimes it acts as if it will stop but then catches and keeps going. But next cycle, it stops. Same place🤷🏻‍♀️