Age-related concern: 13-year old filter had never been serviced.
Used a phillips screwdriver to remove 4 retaining screws located on the top leading edge of the unit, just above the door. Note the screws on the far left and far right are shorter than the middle two. After removing and cleaning the plastic vent, the small, square charcoal filter is revealed in the center, and is easily removed (noting its installation position first!). Take advantage of the opportunity to thoroughly clean the inside using a cloth soaked in degreaser before replacing the filter, the vent, and the 4 screws.
Really easy for a 75-year old female; just spent more time reading the online manual than actually installing the light bulbs to find out where to access the light bulbs.
The close door warning kept coming on and the microwave would not run
Don't waste your time with other parts stores online. Partselect sells quality parts and they arrived 2 days early. I purchase a door switch from another online store and the switch was defective.
Removed the two screws hlolding the old vent in place. Discarded the old vent. Snapped the new vent in place and attached with the two screws previously removed.
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.
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.