Unplug the microwave from the wall.
Remove the screws from the outer cabinet of the microwave. How many screws depends on the Maytag model. Lift up on the cabinet to remove it.
Follow the power cord until you reach a box containing the fuses. Locate the fuse that is broken by inspecting the fuse glass for breaks or burn marks.
Remove the broken fuse using a fuse puller, or by hand. If the fuse is ceramic, touch the probes of a voltmeter set to the ohms setting to each side of the fuse. The fuse should read zero. If it reads infinity, the fuse is broken and needs to be replaced.
Insert the new fuse into the microwave. Replace the cabinet. Plug the unit in and test.