Help! Being a brilliant thrifty shopper ( ? ) I purchased a beautiful Kenmore Elite Microwave oven on eBay. It was a demo unit, and for six months it worked like a dream! The nightmare started early this week, when suddenly it refused to heat even a wee cup of water. I literally absorbed the manual that came with it, and found nothing describing what was happening in the troubleshooting guide. I made sure that there were four inch clearances all around it for proper venting. The outlet power had not changed, and I even moved it to the outlet our refrigerator is on to see if that could be the problem. No change. The only thing that heated up was my temper. Help! Should I just be grateful for the six months of good use and learn how to exist without a microwave? Praying it is not the magnatron...

Thanks!

The magentron tube in the microwave is probably gone south. I can't think of anything else that will cause the problems you're describing.

Once you go through this, you should be good too go, Good Luck:
Notes on the Troubleshooting and Repair of Microwave Ovens