Above the microwave door there is an exhaust grating. Remove the three screws on the front and the three above it mounting it to the body. Pull the grating away to reveal the two long extension screws that connect it to the rear plate. Turn the screws counter clockwise to release the oven from the rear plate. Be sure to have your helper there ready to catch the microwave with you when it begins to fall away from the wall.
Tom M. Seattle, April 2007