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.
Rep knew exactly what I needed when I described where the part should go on my microwave - price great - shipping great - installed in seconds. Thank you!
Opened the door. Removed the top vent cover. Removed the torx head fastener located at the top left of the door above the hinge. Removed door. Cleaned the unit vents and chassis. Installed new door. Re-installed the top vent cover.
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.