Furnace clean and tune. Cycled system. Checked heat exchanger. Found all chambers have rust and corrosion. Did not find cracks with the camera. Checked, removed, and cleaned burners and flame sensor. Both ok. Checked igniter. Tested ok, some signs of getting worn. Ok at this time. Checked and adjusted gas pressures to maximize efficiency. Checked and tightened electrical connections and clamps. Cleared drain lines. Found ventor motor and blower motor bearings showing signs of getting worn. This is causing more noise in the system. Found ventor motor is leaking water. This is causing a lot of rusting in the burner compartment. Also found there is rust damage in blower compartment. Transition assembly is damaged and should be replaced along with ventor motor. Preformed combustion test. Found normal levels in exhaust. No CO found in airstream. System is showing signs of getting worn, but operating normal at this time. Average life expectancy for this unit is 14 years. Future failure is ex