Hi Brian. Thanks for the question. I believe you're looking for the small white actuator switch.
The Hamilton Beach 990043400 Cup Guide Assembly does not come with the actuator switch, but we do sell the switch separately on it's own. I've included the part below for your convenience. We do have another part number (which I've also included below) that is the cup guide assembly paired with the actuator. Tundra Restaurant Supply sells 3 variations - the cup guide alone, the actuator alone, and a cup guide with actuator kit.
Thanks again for the question.
Answered on 1/25/2013 by Andrew Call from Boulder, CO