You could have a bad/weak transformer and/or primary controller. This is not a diy type repair as you are fiddling with 10,000V on the transformer. Also, you do not "clean" an oil burner nozzle, you replace it with an identical replacement part. The numbers on the lands of the nozzle indicate firing rate and spray pattern. Your furnace rating plate should specify the correct nozzle. The nozzle gets plugged from the back side. From your description, you are getting oil which is then permeating the house. No ignition is the problem, but be aware that an oil burner MUST be set up with an oxygen analyzer to get the best efficiency. I understand not wanting to hire this job out, but you have about zero chance of getting this to operate well/properlyefficiently without a proper cleaning first and set-up second. Wish I had better news for you, but you will spend the service call money in oil due to poor performance anyway.