Thanks Wallew that's a much appreciated guesture, but I think I've got it figured out. It seems to be working great now. It's the pin with a head that actually goes through the front of the slide stop. No it's not just falling, but it's just loose enough to come out a couple of mm and keep the slide stop from engaging the mag follower so the slide wont catch at last round. I could see where it had been staked twice from the factory, and did it again.
Woadyurt that's a great idea, just sounds like it might be hideous. No offense. I'd love to see a pic of both sides, because it sounds very functional all the same. I'm thinking about replacing, as needed, every pin without a head with roll pins. I read on here about someone doing it, and it sounds like a great idea.