Ronald M Chino Hills , CA November 29, 2014 Appliance: KitchenAid 5 And 5.5 Qt. Stand Mixer / Professional 550 - Bowl Li KV25MCXCU5 Kitchenaid Mixer Kv25mcxcu5: Stripped drive and worm gear. How to replace Worm Gear. Removed damaged gears, cleaned unit of all contaminated grease, and re-assembled gear box with new approved grease. Do-It-Yourself Rating: Repair Time Estimate: 30-60 minutes