Lionel the one in the middle still might be good if it holds water just sitting there. Many of the heaters get ruined by people pressure testing them with no clamps. The heater opens up like an accordion and gets about an inch bigger plus I avoid pressure testing, no reason. Moreover, the pressure for those systems is only 4psi. What I am saying is if the heater hold water statically, clean it with hot to warm soapy water over the sink and shake it and dump it over by hand until all the scrap comes out. They are actually kinda rugged if no one poured chemicals in there and or the battery acid did not get on them.