Hi Joanne, thanks for your quick response.
Based on what you are telling me, the most likely problem on your MW is it has a bad magnatron tube. This is the main component that is used to produce the energy that make the food hot. The part usually last for longer than a couple of years and it is possible that you may have an extended warranty on the part. The part looks like this. click here
This is a repair that I would not recommend be done by a novice as there are hi-voltage components that need to handled with care.
Check your user manual for the warranty details. Hopefully you have coverage for the repair by GE as the cost would be in the area of $200-230 to repair it.
I know that this is not exactly what you wanted to hear, but I want to give you the most honest appraisal and answer to your question and the problem, so you can make a good decision on how to proceed.
I hope you feel the same way and please rate my help to you tonight positively for JA.
If you still have any questions, just ask and I will do my best to help you out.
Thanks for chatting with me tonight.