12 year ol KitchenAid Superba 42 making a loud rumbling noise intermittantly.

It really sounds like you have 2 problems, neither of which is likely to be fixed, unfortunately.
One is the noise, and it should be a problem with the wheel that drives the turntable.
There is a belt driven pair of wheels, and I think yours is broken. Then, the lack of heating, is likely the "magnetron".
That is the large and heavy unit that makes the mircrowaves to cook the food.
Very few places fix these anymore, because the cost of the parts & labor will be much higher than buying a new one.
God bless our efforts.

Whirlpool Microwave Buzzing Loudly - ApplianceBlog

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Aug 12, 2011 - 10 posts - ‎2 authors
My Whirlpool MT4155SPS-2 microwave oven has recently started to buzz loudlywhen operated. The sound is getting louder and more frequent ...

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next to the compressor is a relay called a klickson

You can get engineer to replace for about $120 or buy one for about $20

Check the fan on the back and blow air through it to clear any dust accumulation.

If this noise happens when the compressor turns on and shuts off it is called a compressor knock. All the internal workings of the compressor are supported by springs, over time the springs wear out and become weak. When the compressor stops or starts the tourq causes the internal parts to hit aginst the casing of the compressor. Sounds like a clunk clunk clunk noise. If you can deal with the noise do not go out and replace the compressor cause it will work just fine like that.

hello hope this helps , these guys realy help full with
samsung fridge freezer problems

It sounds like a failing magnetron. Sometimes they can be intermittent before they finally fail for good.

Chances are your oven has a 5-10 year warranty on the magnetron.

Please note that FixYa is not currently notifying us Experts when Clarification Requests are answered.

To allow us to help you effectively (at no charge), please post a NEW problem to FixYa, and please include your brand name and the full model number from the tag in or on the unit, and your detailed symptoms.

A loud buzz, hum, or groan is usually a shorted high voltage rectifier diode, but a sound like gurgling into an empty coffee mug is one symptom of a failed magnetron, and yet the mag can be bad without that sound.

Some kenmore fridges have a 10 year warrantee on the compressor and sealed unit. CHeck with your local Sears store if your's is one of them.

if the noise is a rumbling sound tha that would be your roller's.the other problem sounds like a bad timer.time to think,do i put that kind of money in a 12 year old dryer or get a new one.

That sound is usually your icemaker calling for water. you can turn off your icemaker by lifting the little arm on the icemaker. As the icemaker calls for water the valve will be activated and will hum. This sound is usually not very loud. If your valve is making that much noise you may consider replacing the valve. The part number for you water inlet valve is #2315533 The retail price is $60.18 . I do have these on hand and available to ship out today if you need one. Please just let me know. You may also consider replacing your filter if your refrigerator has one. Thanks and I hope this will fixYa
Michael Anderson
Anderson Appliance
(865)945-3808