I haven't fixed MWO's for years but I used to do it professionally (and I had service literature). Now I'm just trying to help a friend and don't have any service literature. This unit is right at 10 years old. Everything seems to run and work normally except the heating. It sounds a little bit like it is grumbling when it is on though. There is only 25ohms between the magnetron pins and the case ground. I'm assuming that means it is shorted and needs to be replaced. The H.V. diode doesn't appear to be shorted. Can someone confirm that reading is way too low and that I need to replace the magnetron? Thanks.

check your diode with your ohm meter, about 20k scale. take diode out and place meter leads on opposite ends. if the diode reads continuity reverse the leads, if it does not read continuity the diode is good. the diode only reads continuity in one direction. if it does not read at all it is bad, if it reads both ways it is bad, one direction only. if you are familiar with the low voltage side of the hv transformer, "primary voltage 120v" then you can see if you have 120v there when you run the microwave. if you have 120 on primary side the problem is in the high voltage side ie magnetron, diode, or capacitor. the fact that you say the microwave is grumbling usually means the magnetron or the diode is bad. my guess after 32 years of repairing them is that you do indeed have a bad magnetron