I'm betting that Jason is right, its not the valve that is leaking, its an O ring in one (or more) of the gear cylinders that is letting air "blow by" from the high pressure side to the low pressure side. Remember, the retract valve has to exhaust air out of the low pressure side, so the leaking air will ultimately be coming out of the retract valve - even though the retract valve is not at fault. I've never had a retract valve have a really big leak that lets out all of the air quickly, but almost every retract system I've installed has had a "blow by" leak when the system is first exercized. You should take the air line off of all of the cylinders and inject some of the BVM thin oil into each one. Move the gear back and forth slowly after the oil is in there to spread it around. Then reconnect the air lines and try it out. It may take overnight for the oil to make the O rings "swell" enough to completely seal in the cylinder...

Bob