Originally Posted by MIballer
Hold the trigger down if it still leaks its the on/off if the leak stops its the power tube or orings on the barrel.
What this guy said.
Just to add one bit of info to his post. If it's the Power Tube (PT) that's leaking, it very well might be your PT spacer. If you have an older mag. It would have a spring and those springs have a tendency to crap the bed. They sell PT spacer kits that work great for the marker. They're solid brass or aluminum so once you get the proper spacer you'll never run into that problem again.