Ron P Yucaipa , CA January 09, 2020 Appliance: Amana Commerical Microwave 550.018 Amana Microwave 550.018: A gear was worn. How to replace Stand Mixer Planetary Shaft Bearing. Replaced the worn gear, planetary shaft bearing,worm gear thrust bearing and motor shaft seal. Also filled the gear case with food grade grease. Do-It-Yourself Rating: Repair Time Estimate: 15-30 minutes