Is my magnetron faulty?

Whirlpool WMC50522AW
-Oven heats weakly--won't boil a cup of water on high after 5 minutes -Draws only 300 watts on high (rated 1200 watts) -Measures -10KV DC to case at Magnetron terminals on high (10 to 1 high-voltage divider measures 1KV on voltmeter) -diode and capacitor appear to pass simple out of circuit tests -magnetron did actually pass simple resistance tests
Looks like the magnetron is faulty? Magnetron PN: 2M248J (no suffix) Thanks. My first post here.
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On Friday, September 16, 2016 at 2:28:51 PM UTC-5, rlyoung wrote:

Reduced power is common to aged magnetrons, but replacement costs can easily be more than what you paid for counter microwave ovens.
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On Friday, September 16, 2016 at 6:45:48 PM UTC-7, snipped-for-privacy@hotmail.com wrote:

Thanks for your advice. For the record I think my initial voltage measurements were inaccurate (too high) due to test equipment mismatch, but in any case the voltage is 50% higher than a working 400 watt oven.
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snipped-for-privacy@gmail.com Fri, 16 Sep 2016 19:28:48 GMT in alt.home.repair, wrote:

And, you know for sure it's going to 'high' right? Rather, you know for sure the relay is being closed AND it's staying closed for more than a few seconds at a time?

How long is the 10kv power being provided to the Magnetron? For a second or two, or is it consistent for a short (but longer than a few seconds) period of time? When you performed the resistance tests, did you also check the heating element? it'll be the smaller diameter wires you find on the Magnetron; not the ones you already tested for power.
If the element is bad and/or the transformer winding that provides it a much much lower voltage is, the Magnetron will not work even if the Magnetron tube itself is otherwise okay and the proper voltage is being applied to it.

That might be the case...
from my experience, power settings on a microwave are actually times when it'll run the relay that powers the magnetron and associated components. The magnetron (from what I've learned with the microwaves I've torn into) doesn't have a 'power setting' it's either running or it's not running.
It sounds like you measured the high output voltage that actually runs the Magnetron. Did you also check the voltage intended for the heating element? It's much much lower.
Since you took a measurement, how long did you take the measurement for? A second to confirm power was flowing and at what level, or, did you leave it connected for the cycle? I'd try leaving it connected for the cycle (if your meter is okay with this) and see how often it's dropping out. You may have a problem with the controller board and/or relay.

It's a Toshiba Magnetron. You can purchase a new one online for around $50 or so.
http://preview.tinyurl.com/hac453o
That link will take you to Amazon. Be sure you get the two letter code and compare it to the one listed as being available. It's only for GS/GM models. I don't know which one you have because you didn't provide the entire part #.
If you haven't already run those tests I mentioned, I'd go ahead and do so before spending $50 on this part. You could just buy another Microwave for a little more than the cost of that part. Unless you really like the one you have and don't want to replace it outright.
Based on your detailed post, it sounds like you know what you're doing so I won't waste your time advising you not to muck around with these things. :)
If I may ask though.. what is the make/model of the meter you used to test for the high voltage?
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snipped-for-privacy@gmail.com Fri, 16 Sep 2016 19:28:48 GMT in alt.home.repair, wrote:

Are you sure that wasn't 5kv or so? 10kv seems a little high to me. I suppose it's possible, I have no first hand experience with your particular microwave. The ones I've seen (including a few commercial ones) were using 5kv transformers...
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On Friday, September 16, 2016 at 12:28:51 PM UTC-7, rlyoung wrote:

Diesel, I just saw your posts. Thanks a lot, really. When I can I'll get back to the project and take into account your comments. Probably in a day or two.
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