Unplug the power cord. Turn off the gas supply connected to the unit.
Insert the putty knife or flat knife into the gap between the top panel and the front of the oven range. Press the knife into the internal clips 4 inches from each front corner to unhook them.
Lift the top panel up and off the unit. Set the panel aside.
Remove the screws holding the igniter to the burner assembly. Unplug the electrical connector from its harness.
Slide the igniter out of the metal enclosure. Slide the new igniter in its place.
Plug the electrical connector into its harness. Install the screws that hold the igniter to the burner assembly.
Replace the top panel. Press down on the panel to engage the internal clips.