I have a KitchenAid mixer, model K45ss. There is no power, nor humming. The cord is good. I have replacement carbon brushes, but this model is about 35 years old and there no little square box in the upper left hand corner of the brush holder, as in later models, to help with alignment. That is the 1st question. How to align the brushes? What else could the power problem be: circuit/phase board, speed control board, hall effect sensor (whatever that is)? Any advice is greatly appreciated. Thanks!