Mower Engine Noise and Hard vibration

I am in no way, shape m, or form a mechanic but have always liked to solve things on my own but I am finally stuck and need some help. Seems like all the mechanics are on a 4 week back up so I figured I'd reach out on here. Here's an explanation of what's going on and what I've done so far.

Engine: Briggs 26 HP
Model #: 44P77
Type: 5157G5

As I was mowing yesterday I heard something which sounded like a screw rattling around in the flywheel or engine and a hard vibration and seemed to lose...

Mower Engine Noise and Hard vibration