Parking lots are where I do a lot of my gun deals. Totally legal and customary in AZ. I traded an AR-15 and no one batted an eye at the other guy looking it over and aiming it in broad daylight.
Anyway, I think I found there problem. Here's the slide catch.
Looks like there's a dimple on the inside of it, which is hanging up the spring action. I compared it to the slide catch on my other Springfield 1911, which did not have this dimple. I don't how it got there, as this gun is definitely not used enough to have developed this dimple from wear and it seems like there's no point in machining it there.