The Planetary Assembly is an OEM part for Whirlpool stand mixers. It is a critical component responsible for the mixing action, ensuring that ingredients are evenly combined by moving the mixing attachment in a planetary motion around the bowl. Causes of a bad planetary assembly can include wear and tear from regular use, damage due to overloading the mixer, or lack of maintenance. Over time, the internal gears and components can wear out or break, affecting the mixer’s performance.