Hey Guys. I have been building this cocker pump for a while now and now I have this problem with it. When I turn the Co2 valve on, the gas seem to go right through the gun. I just got it back from the shop. He change the valve inside the body, Mac Dev I think. Anyways it seem to work fine at the shop. I told him I wanted the 12ounce tank filled. When i got home I screwed the tank on and when i opened the on/off valve, like i said the gas seem to go right through the gun and then it started getting cold so i stopped. I'm taking it back tomorrow. Don't want to do anything to it so he can't say i did something to it. Any help as always will be greatly appreciated. TIA btw this is my first post. I hope i can learn a lot here. I tried to look for cds on the web for repairing cockers but couldn't find any so if anyone knows of any I would appreciate that info as well.