I have a Crosman Nitro Venom .177 that I love, but unfortunately, I can't get it to launch a pellet. Is it possible for the gas charge to leak off on these guns? When I put a pellet into the chamber and try to fire it, there's not enough pressure to push the pellet out of the barrel. It's a relatively new gun with less than 200 rounds put through it. Any advice would be greatly appreciated. Also, there is no repair shop within 200 miles of where I live.