Just purchased a Big Country 3850mb and the atwood water heater is leaking. It is leaking into the storage compartment area. Have tightened several fittings and the shower drain. It is now only leaking when the hot water is turned on. The wood base below the water heater is wet and small amount of water on top of the black electrical box below the hot water outlet. Have tightened both the hot and cold water. Would this be because of the check valve that I have seen in some other posts? Any help would be greatly appreciated. Everything else has been great with the camper.