[jspatz1]

Sounds like the valve spools may be sticking. You might want to lubricate them by sending a few drops of light oil through them (just drop it in the input line.) If they are used and have been sitting around for awhile, the o-rings in the spool can get dried out or contaminated and stick. These valves were meant to be used with lubricated air in industrial service, yet in robotics we ask them to work without ever seeing any oil. The spring return depends on the valve being lubricated to work properly. I have yet to ever find a team that has lubricated their valves (the cylinders need it too) by sending some oil through the lines, so I preach that whenever I can. I suspect it is the cause of many teams' problems with valves.