What is the typical thing to look for that broke when my lawnmower hit a
stationary object?

I've hit much tougher sets of rocks than the little things that all of a
sudden caused my Craftsman 18 inch push mower to wobble (I think) and run
badly and now it won't start.

No big deal. Lawn mowers are only a few hundred dollars, and a repair
person probably will only charge half the cost of a new one.

But, I wonder if I take it apart, what would I be looking for?

I've never taken a lawn mower apart but I've fixed things and have all the
mechanics tools for my car, for example, and a lawn mower can't possibly be
too complicated.

What would I be looking for. What is the typical thing that breaks when a
lawnmower hits an immovable object?