Ignitor did not spark when turning the know

Had to remove the 4 range knobs, and the oven knob and then the facie. Two screws under the end caps and two on each side from the back on each end. Design defect: one of these screws which attaches through the frame to the facie also attaches the support which holds up the range top. Take that one off last. Remove the two wires that attach to the oven light switch. After detaching the power supply to the defective ignition unit, it just pulls right off. Push the new switch on over the knob shaft and reassemble.