Speed Sensor and Control Board for the older Style Kitchenaid 6 Professional e.g https://encrypted-tbn0.gstatic.com/images?q=tbn%3AANd9GcQPbYMXGZQeETYXaHhyXVWp4kej0ki5_0__niUBmbcXMXmBYprGvlcmBUmjYx7zWi9PAB3P8UqR&usqp=CAc Price new $75 Also includes the Hall Effect Sensor