Once you have disconnected it from the power and verified that it is disconnected, the toughest part is looking at the case and removing the screws to the case. The case normally slides out after removing the screws and you'll see the fuse. If you have a good multi-meter, use it to test the fuse after pulling it out with a pair of pliers. The fuse is normally 20 amps, but could be a 15 amp. Take the old fuse to a local source (Radio Shack carries microwave fuses); the letters and size on the fuse need to match what you buy. I usually slide the case into place but not screw it back on, plug the unit back in and get a cup of water to test the operation. I can't emphasize enough the need to kill all power. I am not familiar with this exact model, but everyone I have worked on (10 or 15) are basically the same. The fuse is almost always behind the control panel, and the trouble I have found is deciding how to slide the cover off and getting the right screws removed without removing the wrong ones. Good luck.
Travis Electrician, March 2008