Unplug the microwave oven from the wall or disconnect the power at the circuit breaker.
Remove the screw on the right side of the light bulb cover and let it hang down.
Pull the bulb out of its socket carefully; the bulb could be hot if it was recently used.
Push a new 120-volt (20-watt max) bulb into the slot, replace the cover and tighten the screw. See Tips for more bulb information.
Connect the power supply and test the bulb using the "Surface Light" button in the bottom right corner of the control panel.