No igniter spark on torpedo heater

I aquired a used and abused Master B300D torpedo heater.After clearing a clogged fuel system I have no spark across the electrodes.It is a 2 electrode system, arcing at the fuel nozzle.There is no manual availible from the mfg,as it is a discontinued model. Where should I position the electrodes? Should they be arcing to the nozzle or in front of the nozzle and what should the gap be? It is now about an inch. I did have spark before I serviced the fuel system.Apparently the electrodes were disturbed during servicing.Any advice would be appreciated.