So after replacing the safety screws, I took the thing out for a run.
First round fired fine. Except something was amiss. I was looking down the inside of the slide. The firing pin was missing. It appears that somehow the pin moved forward enough that the retaining clip fell out, then the pin came out. After some searching, I found the pin, spring and clip laying on the ground.
Ok, so I reinstalled them after clearing the weapon. Reloaded and fired again. This time, the spent case ejected, but the slide hung up on the hammer because the pin clip was hanging halfway out.
Cleared again and pushed the clip in. Fired the rest of the magazine without problems except that the safety was dropping halfway to the "safe" position on each shot.
So far I have deduced that the safety thing probably requires me to take it apart and bend the tabs so they fit tighter. Not too hard.
On the firing pin, I think a weak firing pin spring is allowing the pin to slide forward as the slide is moving backwards, which lets the clip fall out. When the slide stops moving, the pin keeps going and flys out the back fo the slide. Solution: need new firing pin spring.
Any other theories?