Locate the main breaker panel in your home and flip the switch that controls the oven circuit to the "Off" position.
Shut off the gas supply by closing the valve on the gas line at the rear of the oven.
Remove the access panel on the front of the range. This will usually be located on the bottom of the unit.
Locate the cylindrical metal spark ignitor inside the compartment. It will be mounted via a bracket next to the burner.
Unplug the wiring harness from the rear of the ignitor and remove the screw holding the ignitor in place.
Remove the ignitor and fit a new one in the bracket. Replace the screw and plug the wiring harness into the port on the ignitor.
Replace the access panel of the Whirlpool range.