MT4078SPB1 Whirlpool Microwave - Instructions

1. Remove the trim frame off of the front of the cabinet (4 Phillips screws). At this point, take glass plate and turntable frame out of unit. 2. Slightly lift the unit off the cabinet frame (which is attached to the cabinet) so the feet on the microwave allow the unit to clear the frame and then remove microwave from the cabinet. 3. Once slightly removed from the cabinet, unplug the unit before completely removing it from cabinet. 4. Take 2 Phillips screws out of the side panels. 5. Take about 6-7 T20 Star Pin screws out of the back of the panel. (This may require you to purchase this special tip if you don't have it in your toolbox). 6. Slide the microwave cabinet toward the rear of the unit (the front portion clips into the frame ... don't try prying it off because you'll damage the unit). 7. Completely remove the microwave cabinet housing. 8. Be careful not to damage or catch any internal wiring inside the unit while the cover is off. 9. Turn unit on it's back and remove 4-5 Phillips screws holding the bottom cover in place. Remove bottom cover. 10. Now notice that the turntable motor is completely exposed. 11. Remove the wiring harness from the motor (notice which connection clip has the black wire). 12. Remove the one Phillips screw holding the motor to the frame. 13. Clean around the area in case food spills may have gotten into the area. 14. Insert new motor, put Phillips screw back in and attach power connection. 15. From this point on, just reverse steps to re-assemble microwave and put back in cabinet. 16. Test new turntable motor. 17. Enjoy the smile from your wife because she can now use the microwave!

removed microwave cover screws, unplugged motor, screwed on new one

The door was not engaging the micro switches properly no doubt from 10+ years of wear. The upper switch removed fairly easily but take care not to tweak the plastic brace too much or it will snap. The lower one was the tricky one. After much examination I noticed that the trick to remove it was underneath the brace. Take a butter knife (no joke) and insert it just under the old micro switch and gently press down twisting the micro switch every so slightly til it releases. The replacements snap back in with no trouble. The microwave is working much better now, though not perfect.

Since others reported similar problems and it was just the fuse we tried that first. That wasn't the problem so we ordered the Door Interlock Switch Kit. Shipping was very fast! Our microwave had 3 switches. My husband asked how to know which one to switch. I read that one person just did process of elimination. Luckily ours worked on the first change out! So happy to have stumbled across this site and not have to buy a whole new microwave.

remove 4 screws from top, front louvered panel snaps out. remove 1 screw from top of keypad, keypad pivot's forward and can be removed. There is a white mounting bracket inside left. Remove two screws, one top and one bottom, bracket lifts up and out. 3 sets wires are attached, mark them with masking tape, top, center, bottom and pull out plugs. They can only attach one way. Using a very small screw tip, lift plastic latch from switch, it rotates out and is removed from the pivot pin. reassemble in reverse order after switches are replaced