Get to the spark module and switch ignitor wires around (do not switch the main power wires coming into the spark module which are usually red & white or black and white should be 120v) Take the one that's not working and plug it into another spot in that block it doesn't matter which one you swap it with all ignitors should come on no matter what knob you turn on. If the burner works fine after the swap replace the spark module and if not check your ignitor wires/ignitor or burn switch harness. Do no try to do a voltage check to the ignitor from the spark module the voltage is too high and will burn up your meter. Ohm out the wires from the spark module to the ignitors also to make sure they aren't shorting out.
Cabinet Parts parts for Dacor SGM365 - AppliancePartsPros.com