My first 2nd Gen P3AT has been great. I purchased a second as a backup, and because I liked the grey grip. The second one was pre-owned, unknown number of rounds fired, but appearance looked ANIB. Worked great for the first 200 rounds. Then started to have fail-to-feed, fail to eject issues. Increasing frequency until the other day I had 9 malfunctions in 30 rounds fired. In each malfunction, the slide had binded up in the 2/3-open position, and either the fired case was not ejected, or the live round was not fed/chambered. I could hand cycle the slide, but it was obvious that the slide was stuck with some friction against the frame. I changed the recoil springs to a new set with no change in the results. The malfunctions occurred with all four magazines I have. Ammo was factory Speer 90 GDHP, Federal 95 FMJ and Federal 90 JHP. During hand cycling the slide, I could not reproduce the problem. Field-stripped, I could not see any damage. My original P3AT works perfectly. Any ideas?