I just reassembled my gearbox. I have taken apart and reassembled it a few times before without error, but this time I think there's a problem. When I fire the gearbox, the air nozzle stays back after the shot, and then when I fire it goes forward and then keeps ending up all the way back. I'm not sure what is happening. If anyone has any theories please let me know. Thanks to all who reply with any information regarding the problem.