Unplug the range from the electrical outlet. Turn off the valve that supplies the gas to the range.
Open the oven door and remove the racks. Set the removed oven racks aside.
Remove the screws securing the floor of the oven, using a flat-head screwdriver. Lift the floor out of the oven and set it on a padded surface until your repairs are completed.
Unscrew and remove the wingnuts from the protective panel shielding the oven's gas burner assembly. Set the protective panel aside.
Locate the ignitor component to the left of the pipe-like gas burner. Remove the screws that secure the ignitor to the oven.
Pull the range away from the wall. Take out the four screws that hold the rear service panel to the range cabinet. Remove the service panel to reveal the spark module.
Disconnect the ignitor wires from the spark module. Pull firmly on the plastic wiring connector to detach the ignitor wires; do not pull on the wires themselves. Remove the ignitor component from the oven.
Line up the screw holes on the replacement ignitor with the screw holes inside the oven; replace and tighten the removed screws. Plug the ignitor wiring connector into the spark module.
Reverse the process to replace the removed range components. Plug the range into a grounded wall outlet and turn on the gas supply.