Went to the range yesterday to see if my two spring fix for FTE problems had fixed the problem. After firing six rounds with no FTE issues, the 7th round failed to feed. When I checked the gun I found that the Assembly Pin had partially worked its way out of the gun. Before going to the range I had cleaned/greased the PF-9 and manually worked the slide and dried fired using snap caps. Everything worked fine. I'm sure I had put the gun back together correctly. Can't figure out what would cause the Assembly Pin to work loose. Any ideas or suggestions would be appreciated.