Well I had a friend who has a shop look at it. The connecting rod broke. He said a new engine, with labor and all, would cost $700. Mystery solved, I suppose.
I tightened up a couple of more motor mount bolts. Still won't start.
I found a bolt in my yard. Is there a 5th motor mount bolt? 4 are in. Not sure where this one goes if that even is what it is. Before I tightened the other motor mount bolts, the engine did shift. Now, it does not.
This is my starter. Looks like metal. Not worn out, to me, anyway. I do not understand why it would start before I put the motor mount bolt in it but not after.