He couldn't get it out so he bolted it back on and let the jacks back down.

 

If it's the "brushes" and I've heard sometimes hitting it will help it out, does this have to be done while you're trying to crank the car? In other words, hitting on it and then letting jacks down and hooking battery back up wouldn't have same affect? If the starter ends up needing replaced, I would really like to get it cranked so I can take it to the shop.

 

It is not as uncommon as you would think. I am not saying that is what is wrong but bearing damage can occur while the motor is hot, it may only show up a fluctuation in oil pressure but once you shut it off and let it cool it becomes too much for the starter to start. I have even seen motors with bearing damage that would start with a push start by a truck and ran semi decent but no way would it start with a GM starter. Once they do start their life is measured in minutes. Of course you would only try with a motor you planned on scrapping.

98% of the time it is just the starter. It is just before I swapped the starter I would have turned the motor over by hand to see if it felt ok, it only take 30 seconds. But for that you would need to know what "normal" felt like.

 

That normally help when there is a dead spot in the starter. The tapping shifts the starter off the dead area, but it won't hurt to try. In your case it could be a lot of crud. If it is crud then a few taps may help.

 

For that to work, it needs done while trying to crank, right?

 

Right. Hitting the starter is a trick to possibly free up a stuck solenoid, not make a bad motor run.