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