You do not have to be a highly-experienced troubleshooter, in order to judge the wisest approach to this troublesome issue. As is true with most such issues, the troubleshooter’s approach should represent an effort to eliminate the problem that would be easiest to solve. In this case, that means carrying out an examination of all the sides and angles in the microwave’s heating chamber, including the ceiling.
What to look for in that chamber
Did any food splatter or drop into the microwave? If it did, it could continue cooking the next time that the same small appliance gets turned on. That continued cooking could trigger production of sparks.
Did any grease shoot up from heated food and stick to the ceiling? If it did, it would undergo further warming the next time that some other food had to be reheated. In order to eliminate chances for further sparking, the grease spot must be removed. Indeed, the entire chamber should receive a good cleaning. Next the troubleshooter must make note of when the sparks have been spotted. Was it a time when the microwave was turned on? If so, then it appears that one of the following parts could be malfunctioning.
High voltage diode
There could be a short or an opening in that specific diode. Unplug the appliance and remove the cabinet. Because you have taken the proper precaution, you can discharge the high voltage capacitor. If that does not solve the problem, then you should plan on locating a multi-meter. Hopefully, you have such a meter close-at-hand; you will need it when you test the diode for continuity. Note the reading that shows up during the testing process, and then plan to take the appropriate action. If the meter has produced a reading that signals a low voltage in both directions, then the microwave needs to be replaced. If no reading has appeared on the multi-meter, then the needed action becomes all the more clear. It is time to start looking at all the microwaves on the market.
Do not think that the stirrer’s function does relate to the movement of the turntable. Rather it concerns the action required to enhance the capabilities of the microwaves. The stirrer has one function: ensure distribution of energy produced by the appliance’s radiating waves.
A malfunction in one of two different parts could keep the stirrer from ensuring the distribution of that energy. The broken part could be the drive motor. Like the rod attached to the wheel on a car, the stirrer will not rotate if the motor has ceased to operate. If that motor seems to be working properly, then it could be that the stirrer’s belt has become broken. There might be other issues that you won’t be able to notice and that are why it is important to call on an appliance repair professional in San Diego Area.