YMMV4205DH2 Maytag - Instructions

Turn off power supply at breaker . Replace old bulb with new bulb .

Part of the support was missing. I had to remove the two switches and put them in the new bracket
Had the switches reversed and started blowing fuses. Reversed them and changed the fuse and it started working.

We needed a phillips head screw driver to remove the single screw holding the light bulb cover in place.
Removing the old bulbs was a little work, because they had come loose from the sockets. We unplugged the microwave, so we could grip the sockets with a tool. I think my husband used a needle nose plier for this.
The new bulbs screwed in easily, and then we refastened the light bulb cover with the phillips head screw driver.

screwed in new bulb

Husband replaced the bulb

Spouse just screwed in the new bulb and reinstalled the light cover plate with the two screws. Took under a minute. Works great.

Repair unsuccessful because they sent the wrong part, even after I questioned their selection. It is amazing how a company as large as Whirlpool cannot clearly indicate to the people who work for them how to order the correct part. The fault lies not in the individual who is putting the order in but with the company who cannot take the time to make sure that person is successful in completing their job. Will never buy a product from this company again.
As far as the shipping is concerned. It took forever, just to find out that the part was incorrect.
Better luck next time. right?

Just opened the door and dropped in new part and viola!

Used a screwdriver only. The grill vent is not at all durable and stared to crack. The microwave is less than 2 years old.

Removed the old turntable tray, replaced it with the new one.

On top front of the microwave are two Philip's head screws holding the rail on. Remove these screws and the rail snap out the old filter (noting the dark side down) then snapping the new filter in. Replace rail. 10 to 15 minute task.

Remove the two screws to the plastic vent strip at the top of the unit. That exposes a metal cover (upper right) held in place by two more screws. (Found that removing the screw holding the key panel in place and moving that out of the way made for more work room) Remove the metal cover. The HV diode (visible) on one end is secured to the chassis by a screw. The other end is fitted to the HV capacitor. So unscrew one end and pull the HV diode off the capacitor. The replacement fits on like the old one came off. Very simple repair. But it would be safe to short the capacitor terminals to the chassis first. Noticed that it appeared the sparking was caused by the HV diode's outer casing being worn by the asbestos covered wire next to it and laying against it. I made sure the two were not touching, before putting the covers back on. Also, the problem started with an occasional spark when the MW started. It quickly deteriorated to a full, non-stop electrical sparking. You can hear it, smell it, and see it through the top vent. You don't need to remove unit to work on it.

Loosened but did not remove screws that held up microwave over range,removed grill on top by loosening screws that held grill in place.removed small mesh grill on right side of microwave, this gave me access to capacitor ,diode is connected from one lead of capacitor to a metal plate ground,Disccarged capacitor to ground by shorting terminals to ground using a thick insulated screwdriver.Since the diode was screwed to the top of the metal plate I cut it out with a pair of side cutters .I then connected the new diode to the capacitor with my long nose pliers and groonded the other end to a more accessible part of the metal grounding plate.I then replaced all parts in reverse order.Works like a charm.

After removing the over-the-range unit (no small feat!) I had to figure out how to open the case (good puzzle!). Capacitor had already discharged, so it was very easy to reach in, pop the old fuse and install the new one! As per your advice, I found out I was a "28%-er"! Upon re-installation, the microwave "sprang to life"!! Thanks, "Part Select"!! I was already shopping around for a new machine! (Now if you could only tell me an easier way to re-mount this heavy beast over the stove!!!)

Unplug the microwave. Then remove the six screws that hold the lower panel which has the light bulb cover and a couple of vent filters. The light bulb sockets are on a fixture that is connected by a quick connect electrical connector. Disconnect that and the whole panel is free to access the bulbs. My bulbs were very fragile and trying to twist them out resulted in the glass twisitng loose with the base still in the sockets. I needed to use a needle nose pliers to remove the bases and then I replaced the bulbs and put every thing back together