Bolt moves forward when Ion is pressurized.
· Check the largest o-ring around the bolt for damage (bolt sail o-ring, 16x2-mm ID); replace if necessary.
· Check the inside rear o-ring in the body breech section (17/70); replace if necessary.
· Verify that pressure is indeed moving through the solenoid while the marker is idle. For this, you will have to first separate the frame from the body and remove the banjo fitting from the vertical adapter. Then, pull out the circuit board so it is free from the frame, and reinstall the banjo fitting into the top of the vertical adapter. Remove the fitting from the underside of the body breech (the one with the 1/8" microline) and pressurize the marker for a short period of time. Air should leak out the 1/8" microline when you do this. If air doesn't leak, then the soleniod is the problem, and should be disassembled and cleaned, and reassembled correctly.
· If air is released from the microline, disassemble the solenoid and verify that the armature is installed correctly. The black end of the armature needs to face down.
taken from ZDS paintball- ION troubleshooting guide