Ken B Bozeman , MT October 12, 2021 Appliance: KitchenAid Portables - Stand Mixer KSM90 Kitchenaid Mixer Ksm90: Mixer is 30 years old and was erratic in speed and seemed to be partially slipping in the gearing.. How to replace Motor Housing Seal. Replaced the phase control board, the speed governor, the speed control plate and worm gear. The tutorial videos posted by AppliancePartsPros.com were key to completing the change-outs without issue or problems. Do-It-Yourself Rating: Repair Time Estimate: 30-60 minutes