What does it mean if my mixer switch lever clicks but the mixer won't run or buzz at all?

This indicates an open electrical circuit. Possible causes include a faulty plug or power cord, a faulty speed control plate, a wire loose from the brush holder, an open-circuited armature or field, a bad phase control, dirty contacts, or incorrect brush orientation. The speed control mechanism and motor should be progressively disassembled and checked until the open circuit is found. (Appendix B-1, B-3)