Furnace clean and tune. Cycled system. Checked heat exchanger, ok. Ch died and cleaned burners and flame sensor. Igniter was cracked and broke while trying to remove it. Replaced with new igniter. Found ventor motor bearings are very worn causing major vibration and noise during operation. Checked and adjusted gas pressures to maximize efficiency. Checked for CO and XS air in exhaust. Normal levels found. No CO found in airstream. No CO found in airstream. Ventor motor will fail, recommend replacement of motor, office to quote on follow up. System operating normal at this time. Job complete. Upgraded from safety check to full clean and tune