ok marker is leaking out the back cap....o ring needs changing i know, however when i fire the gun, the electrics work and it cycles (fires) but with no 'bang' just a pathetic cough and i can see the bolt going back and forth just feels like theres no pressure there, even when i adjust the front reg it stays the same but then starts to vent from the solenoid so i have to turn it down again..............im baffled, any help apprectiated