Upon arrival unit was off on reset. Checked the history of the primary control and saw that out of the 15 saved previous runs only 3 lit and the ohms were well over 2000 for all 3. This indicates that the cad cell eye was having a hard time seeing the flame. Checked oil flow and had a lot of air in the oil line. Checked the nozzle and saw it had been dripping. Also saw a large formation of carbon in front of the nozzle assembly indicating the nozzle had been dripping for a while. Replaced the nozzle, cleaned the electrodes and removed the carbon buildup and any oil residue. Bled the oil line again and started and tested the system. Had to cycle on and off multiple times to burn off all excess oil from when the system was not igniting. Started and tested the system. Unit is running at 7.2%o2 40ppm co 0 smoke Recommend getting a maintenance done before the end of the heating season as one has not been done in over a year.