Read. Read. Read more. Get an account on AirsoftMechanics. Read more. Watch Youtube videos. Dissasemble and reassemble your old gearbox. Mess your gearbox. Cry. Retry. Break something. Cry. Retry until you get it. Become addicted to airsoft tinkering.
K3vX | Airsoft Gunsmith/Gun doctor in training.
Feel free to contact me in your preferred language and I'll gladly answer.