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I dont like changing parts till you get to the broken one, It gets very expensive. I think you need to double check the 20 and 30 amp circuits coming int the terminal block from the sub panel. turn off the 20 amp and check voltage at tb1 and tb3.The terminal block is different from the old style with black relaysnew style [H2] [1][H1][2][3][4][5] H2 H1 go to heater 1 30amp hot 230 volts across these (turn off 20amp when checking )3 30amp hot2 20amp hot 120volts across 2 and 4/5 (turn off 30amp when testing)4 20amp neutral5 jumpered with 4