I have this new to me Duffy that I bought in the late spring and just started fishing. It has a bus heater, the standard one you see in so many boats. Yesterday I smelled burning coolant, looked and saw what was about 2 tablespoons of coolant that had leaked out of the unit, not out of the hoses or connections. Today it was twice as much. Unfortunately, whoever installed it did not put valves on the feed and return. So tomorrow, I am going to drain her down and install the valves. Are these units repairable, or do I just toss it and order a new one? Thanks.