Unplugged microwave. Removed cover. Discharged the capacitor using insulated pliers, also shown on youtube. I am paranoid so I wore auto shop rubber gloves the entire time. Tested the diode and appeared to work fine. You can youtube how to test it. Good resource. I also did make sure the system was sending power to the transformer block beneath the magnetron using a voltmeter. Was warned via youtube not to test the output side, only the input side. Replaced the magnetron. Microwave works fine now!