So my friend is going to buy a cyma Tommy gun today or the next day if he can find a spring guide to show him how to replace the spring. I have been looking all day and have been having a hard time finding it. He can't afford the 40$ for gearbox to change it and he really does not want to wait a week for it to be ready to use. I would be eternally grateful if someone could either find a guide or show me something that would show me how to do the change ourselves. We need the gun at below 330 FPS.