To follow up on shane3fan: Improperly installed Clippard solenoids will "leak" CO2 via normal flow pattern.
The CO2 should flow in the same path as the word "CLIPPARD" on the label of the solenoid. If the label is removed, look inside the ports of the solenoid. The port with the large hole in the center is the INPUT port. The port with the small, offset hole is the OUTPUT port.