I am having trouble with gas leaking through the gas settling bowl past the closed valve on the side of it when it is turned off. So I was going to take it off and see what the problem is. I can see the gas line takes a standard gas line wrench in about 9/16" or so. But I can't see how to remove the entire settling bowl/valve assembly from the bottom of the tank. Is it just threaded into the bottom of the tank like a pipe thread? And how do I turn it out? What kind of tool is used? And what kind of sealer do I use when putting it back?