Hello, I have done a search with no luck, so here goes. I have a .40 STI Edge stock condition. When I transfer gun from strong to weak (left) hand and engage the ambi safety it fails to fire unless I squeese the heck out of trigger. The second shot is ok. I have filed down the part that activates the safety. I even taped the grip safety in and it still does it. I also polished the sides of the grip safety, as well as tried different length sear springs. I checked for grip cracks and also changed trigger bows in an effort to elimante things. Any suggestions would be appreaciated.