I was kind of in a rush when I typed that earlier. To be specific, the main screws you'll want to check are the ones that are underneath the little panels on the sides of the pistol grip area. Just pry the panels up with a thin flat blade screwdriver or something, IIRC there are a couple of screws in there. Check those. If they've come loose from recoil or something, maybe some VibraTite or other thread locker will help.