Microwave burns popcorn. what part is defective?

If the microwave functions normally while cooking everything else, but is only burning popcorn, there is no component problem that will cause this. You cannot adjust or replace any internal component to make it not burn popcorn. All power levels and program options are contolled by the consumer at the control panel. Refer to your owner;s manual for their recommendations.

If the oven is equipped with a popcorn feature button, it is programmed for a recommended power level and time. This is an ESTIMATED program feature. The manufacturers of both the oven and the popcorn will also give directions that tell you to turn the oven off when the popping slows to about a pop every 2 seconds. Failure to do so can result in burning.

If the microwave does not come with a popcorn feature button, the manufacturers of the popcorn have directions on the outside of the box that tell you what POWER LEVEL and TIME to set the oven on for the desired result. Again, the you still have to listen as the bag pops to ensure it does not burn.

In addition, on some microwave ovens, there is a feature that allows you to select the SIZE of the popcorn bag. Some popcorn manufacturers have smaller snack size bags that don't take as long to pop. You have to select the appropriate size to get the correct program option.

In any case, you never are to place popcorn in a microwave oven and walk away from it. All these program features are ESTIMATIONS based on manufacturers testing and recommendations for the best results. All microwave ovens are different and operate at different power levels. Your best judge is to listen as it pops.

I hope this helps you.