I have an M57 that I'm having operational issues with. It will fire the first round, eject, load the next round after cocking the hammer. Pull the trigger, and it won't drop the hammer to fire. I traced it down to a loose hammer group. It moves enough to keep the trigger from fully releasing the hammer. In troubleshooting the problem, I used a drop of Super Glue to keep the group in place, and it now hand functions normally. I have 2 Chinese Toks and they fire without issue. Anybody else heard of this problem, or maybe know a permanent cure?