Microwave seems to operate but produces no heat...

Went to the Gallawa site and did some tests but I'm still confused from the results I obtained.

While attempting to discharge HC cap, I got no spark at all. When testing, using a digital multimeter (9volt battery type) here are the results I get:

Meter set to 20M ohms:
Across both terminals I get a reading starting at 0.L and readings increasing towards infinity, increasing at about 1.00 ohm per second. When I reverse the probes, I get a negative reading for an instant which then zeros and starts to increase towards infinity, again at about 1.00 per second. This I think is normal.

When I go from either plug to the cap's case I get 0.L no matter which plugs or probes I use. I thought I was supposed to get some sort of reading when doing this. Am I correct?

Also, I tested the HV diode according to Gallawa's site...Setting the meter at R X 10,00 or higher (I set it for 20K). I get 0.L in both directions. That means the diode is open in both directions. I was under the impression that if the diode was open, then the capacitor should have been over-charged and should have given me a very loud pop when discharging it.

I have not looked at the magnetron yet as I haven't been able to figure out how to access it. Everything that looks like it should come apart when screws are removed appears to be tack welded in place. I figured I'd ask these Qs first before delving deeper.

Could both of these items have gone bad at the same time, or does the capacitor appear to be reading properly (I'm not 100% sure).

Also, one site I went to said that one cannot test the HV diode with a digital meter...that an analog meter was the only way. Does this sound true?