I just bought an Orion marker from my neighbor. He was nice enough to sell it to me for $15. He has tons of markers and wanted to get rid of them no matter what the price. Anyway I went to use it a couple weeks ago for my first time playing paintball. When I got there and hooked up an air tank to it the gun would shoot, but it would not re-cock. My neighbor said it was a semi-auto. The guy that worked at the place couldn't figure out what was wrong. So my neighbor took it apart to see why it didn't re-cock. His dad also got into it and said that the cylinders that hold the air in or whatever, are worn down and it could be leaking air. My neighbor kept it to work on it. He cleaned it out and hooked up a CO2 tank and he said it messed up everything inside when he tried to fire it. Anybody have any suggestions on how to fix it, or should I buy a new gun?