My kitchenaid was missing the back cover (received it like that for free!) and the thumb screw was broken Ashley A. • Anchorage, AK • December 28, 2014 Appliance: Whirlpool 4 1/2 Qt. Stand Mixer Classic-Tilt K45SSWH-0 My Repair & Advice I simply replaced the back cover, it only took 1 screw. Then I replaced the thumb screw as well. It took less than 5 minutes. Was this review helpful to you?