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