I have four of these mixers in my bakery and two of them have the "don't shut off" problem. My simple and inexpensive fix is to loop a thick rubber band to the power cord by the back of the mixer and then loop it over the speed knob when I want the mixer off. These mixers are real work horses and I don't have time to take them to the shop for a costly fix. I have to replace the rubber bands about once a month. Works for me!