I just wanted to chime in and say thanks for the great thread....it solved my non-starting KitchenAid Pro 600 Series mixer (Model # KP26M1XER --- 6-Quart --- Purchased in 2012).
The culprit was a defective Triac p/n BTB10-600BW (it is a TRIAC, *not* a Diac like mentioned elsewhere in this...