Water Heaters - Bock oil water heater will not refire

My Bock oil hot water heater which is controlled by a Honeywell R4166B controller will not refire after completion of an initial cycle. The initial cycle operates fine. When the water temperature drops below the preset low setting the unit fires and runs fine until the preset high setting is reached and shuts down appropriately. However, after the initial cycle when the temperature drops below the low setting the burner motor starts but no flane is established resulting in a smoke condition. In that I have replaced the nozzle, regapped the electodes and checked both the transformer and oil pump I am at a loss.