Turn off your microwave, and unplug the power cable from the power outlet.
Open the door to your Jenn-Air microwave. The switch is visible on the side of the interior of the door.
Insert the tip of a flathead screwdriver or hobby knife in the seam where the membrane meets the side of the door.
Work your way around the membrane with the screwdriver or knife, prying out as you go.
Continue until the membrane pops off the door. The switch should pop out along with it.