Turn the handle clockwise in the gas valve connected to the back of the Tappan to halt the flow of fuel. Unplug the electrical cord that provides power for the ignitor.
Pull out and remove the broiler drawer at the bottom front of the range. Set the drawer out of the way.
Turn on the flashlight and direct the beam inside the open front of the Tappan to locate the ignitor. It is on the left, near the front, connected by two wires. The part resembles a spark plug.
Take out the screws in the ignitor plate to release the old part from the inside of the oven. Pull the wire leads off the ignitor contacts, making a note of where each wire attaches so you can reconnect them to the new part.
Slide the wire leads onto the contacts of the new ignitor and hold it in position over the mounting holes inside the Tappan. The ignitor must be turned in the same orientation as the old part. Secure the ignitor with screws.
Slide the broiler drawer back into the front of the range.
Plug in the power cord and open the gas valve on the rear of the Tappan.