Dana S Newark , CA November 29, 2021 Appliance: Model PROFESSIONAL 600 Our Kitchenaid stand mixer made lots of noise ceased to function entirely.. I gained access to the gear box, found a few gears that had broken teeth. I ordered new gears from the "Parts Pros" and replaced the broken pieces...and re-greased everything. Do-It-Yourself Rating: Repair Time Estimate: 1-2 hours