Performed oil burner service today. I measured electrode gap, distances from nozzle, etc. before removing nozzle. I put electrodes back into position. 1/16 in front of nozzle, 1/8 gap between them, and 7/16 from center of nozzle. Lots of fuel no ignition. Tested transformer and received 1'' arc between terminals. No cracks in porcellin and cad cell checks out ok. What gives? Do electrodes get "weak" or is it that they either work or don't? Thanks for all your input.