When mine went bad the tube had become lose up at the base and the o ring went bad . It was covered under warranty and they sent me a new one . You might phone crosman Monday and ask them if they have a parts break down they can send you . I thought they were going to supply repair kits for them but I could be wrong . I very carefully set mine in a pan of water making sure the air inlet was above the water and tried to pump up the rifle and found the leak that way .There is a valve in side that only lets the air flow one way that might be stuck as well .Good luck .Marvin