take that valve completely out and get the lever shutoff type one. the screw in valves are junk, if you over tighten them once they are shot and leak. more tool stores should have them, they are chrome looking and have a black knob to open/close.
i replaced them on my older dewalt compressor, now the dewalt ones come standard with this better valve. if my description above was bad, check out a dewalt compressor and look at their valve.
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