Upon arrival unit was on and running. Found oil dripping from the burner. Took the oil pump and oil burner motor off of the burner and cleaned all oil. Removed the nozzle assembly from the blast tube and found oil dripping from the nozzle and oil in the blast tube. Found a large amount of oil covering the nozzle assembly. Inspected oil pump shaft and seal and found a small amount of oil residue but did not see any noticeable leak from there. Inspected the oil line and did not see any leaks. With the burner not leaking a large amount of oil while running it is difficult to pinpoint exactly where the oil is leaking from. After getting customer authorization we went and got a used nozzle assembly to put in and eliminate that as a possible source of the oil leak. Returned to the house and put a new nozzle in and the used assembly and cycled the unit on and off multiple times. After running the unit for a few cycles we found the oil leaking was slightly less than what was happening with the