what is this?
On the topside of grey tank there is a round thing that resembles a plug about 1 1/4" diameter with a little tab on top. There is a "bead" around this plug which does not resemble any kind of sealant but appears to be the same kind of material as the tank. I have a small leak here. Does this plug come out? Is it replacable? I don't want to attempt to remove and cause more damage.