CLEAN AND CHECK HT. CHECK THERMOSTAT, CHECK AIR FILTER, CHECK HEAT EXCHANGER, CHECK BURNERS AND BURNER OPERATION, CHECK GAS PRESSURE AND FOR PROPER VENTING, CHECK ALL ELECTRICAL CONNECTIONS, CHECK HUMIDIFIER, CHECK HIGH LIMIT CONTROL. LUBRICATE ALL NECESSARY MOVING PARTS, ADJUST BLOWER COMPONENTS. REPLACED STAT UNDER WARRANITY. EVERYTHING IS RUNNING GREAT.