I have two petcocks a CB200 and 200T they're just about the same on the inside. I'm having quite the ordeal over getting the gasket inside the valve to do it's job right. I have new gaskets for them both (the 4 leaf clover ones) It seams that part of the trick is to assemble the valve in the horizontal orentation untill the two screws are down so gravity doesn't pull the gasket down any or I get total valve disfunction. But I'm still getting a small amount of gas passing the valve in the closed position. Anyone know how the heck do you put these things together so that they don't leak??? Is there some sort of sealant I don't know about?