I just had the same problem. Try turning it on and off couple of times might unstuck the solenoid.I called the people @ milwalkee and they told me to take the solenoid piston body apart and lube the plunger assy with wd40??? IMO anything that goes on the actual plunger will go into the co2 stream and into the tank oh well. I used food grade silicone spray and it's still screwed up. I ended up changing out with a clippard solenoid from Rex. It works fine and at least I have some peace of mind now. Hopefully milwalkee will repair it,but I'd probably not use it.Call milwalkee and see what they say. Also when when removing or installing the regulator turn off the main valve on the tank and make sure to back the black knob on the regulator all the way out till it's really loose. Then you can turn the tank valve on and slowly turn the black knob in till you get the output pressure you desire. IMO I wouldn't go over 40psi (right gauge) others might crank their's up more but I found that 25psi works good for me.