Lee P Allen , TX August 02, 2017 Appliance: KitchenAid 8 Qt. Stand Mixer Commercial - Bowl Lift KSM8990DP0 Kitchenaid Mixer Ksm8990dp0 / : Planetary torn in two pieces with small fragments while mixer kneading bread dough. How to replace Planetary Gear Assembly. Replaced external gear and planetary. Heavily applied grease to external gear. Mixer had stopped for an instant and caused the agitator gear and shaft to flip at an angle. Mixer immediately resumed turning and the agitator shaft tore up the planetary. Discovered that the planetary gears appeared to have had very little grease. Do-It-Yourself Rating: Repair Time Estimate: 15-30 minutes