Bad Microwave diode
 

My GE Spacemaker began making a loud noise and then stopped heating. I replaced the magnetron and the noise stopped but it still didn't heat. Using a multimeter and information gleaned from this site I tested the capacitor and diode. The cap seems okay but the diode appears to be shorted. Testing the diode in both directions shows less than 1 ohm. When I connect it to a 120 v AC power source it shows 120 v in both directions.

I have two questions:

1. If I replace the diode should I replace any other component?

2. What, if any, defective component could cause the diode to go bad?

Thanks.

Mike