Steven K St. Louis , MO December 16, 2019 Appliance: KitchenAid 7 Qt. Stand Mixer / Commercial KSM7990WH0 Kitchenaid Mixer Ksm7990wh0: Speed control was jammed. How to replace Gear. So the speed control was jammed on the mixer; would not move. Upon disassembly, the plastic cooling fan for the motor was found to be broken and wedged in the speed control mechanism. Unfortunately, the fan is not available separately! I ordered the motor/transmission assembly with the fan attached and replaced the unit. There is one steel pin that has to be driven out which was difficult. Upon reassembly, the pin was too loose. Fortunately, I had a stainless steel roll pin that was the right size to replace it....... Do-It-Yourself Rating: Repair Time Estimate: 30-60 minutes