Safety guideline for repair of microwave ovens
Work with extra attention, not if you are tired.
Don't do any measurements at the high voltage, this is deadly; the high voltage passes through the insulation of the probe easily.
Unplug the microwave oven first.
Wear electrical insulating rubber gloves, preferably HV-rated gloves.
Use installation pliers to perform the following tasks:
Discharge the high voltage capacitor, as described below, because the charge may be present long time after the microwave oven is unplugged; some people have been died by this charge. Don't trust on the internal bleeder resistor, it can fail.
Connect two decent alligator clip test leads to the microwave metal chassis ground. Be sure that the leads aren't broken.
Clip a resistor of 10K ... 1M to the other side of a test lead and discharge the two terminals of the capacitor one by one via the resistor (use the installation pliers!). The resistor is not critical because it is just to prevent sparks. Note that a resistor of 1MΩ discharges the capacitor of 1μF in 3 seconds.