i've had that problem a couple of times. they get little burrs on the main shaft from dirt or sand grinding around in the little housing. like stewart said, clean it up, a little light sanding and you will be back in business. if you can, i would put a new o-ring in it when you have it apart to ensure that there is no leaking past the valve. be carefull tightening the screws when you put it back on. if you get too tight the inset nuts could break loose and start to turn inside the plastic. MADDOGGY