There are two slots on the valve. Place something small enough to fit in there (screw driver as mentioned above) and just pop the valve off. Place the rubber piece that comes with the winvac in the hole and start pumping (this is assuming you have similar parts to what I have). You can do what arkailija did as well. I had no o-rings so I got desperate, popped the top off and pumped through there. Haven't had a problem since.