1977 MG Midget Rebuilding Lever type heater control valve

Im in the process of putting together a new heater control water diverter valve. Lever type used in the later midgets. My question is do you put any type of gasket sealer on the two gaskets that go between the inlet and outlet part of the valve? Or do you just bolt the unit together real snug. I dont see anywhere in the shop manual where it says to use gasket sealer. Thanks for the advice.

Bill