Yes, it can be a serious problem. The rotating plate is responsible for evenly distributing heat throughout the food and ensuring that it cooks or heats up properly. If the plate is not rotating, it could indicate a problem with the motor or the mechanism that controls its movement. This can lead to uneven cooking, cold spots in the food, or even complete failure of the microwave to heat up food. It is advisable to have a professional technician inspect and repair the microwave if this issue arises. Additionally, a malfunctioning rotating plate can also be a safety hazard. Without proper rotation, there is an increased risk of hot spots forming in the food, which can cause burns when consumed. Moreover, suppose there is a problem with the motor or mechanism controlling the rotation. In that case, it may indicate other underlying issues with the microwave’s electrical system that could potentially lead to more serious problems, such as short circuits or fires. Therefore, it is important to address this issue promptly and seek professional assistance to ensure both the proper functioning and safety of your microwave oven.