[Hawley]

A dirty cad cell will not cause an oil leak. Poor combustion could be some of the problem. Someone mentioned the nozzle. The nozzle has a very tiny orifice that does three things. It meters the oil, patterns the oil and gives an angle of spray. If the orifice gets plugged you may have a spray pattern that is causing impingment of the oil thus it is not being burned properly and create a leak. It is nothing to fool with. You should have a qualfied technician servie the appliance. Good luck. By the way I have been servicing burners for almost forty years.