Unplug the oven power cord. Turn off the gas supply connected to the range.
Open the oven door to the broil position. Lift the door straight up to remove it from its hinges. Set the door aside.
Remove the pans from the oven.
Remove the four screws near the back of the oven floor. Lift the oven floor panel out through the front of the oven.
Remove the single mounting screw holding the ignitor in place near the back of the oven cabinet. Unplug the wire connector leading to the ignitor.
Lift the ignitor out. Put the new one in its place. Install the single screw that holds the ignitor to the gas line assembly.
Plug the wire connector into its harness.
Replace the oven floor panel. Replace the four screws that hold it in place.