The present invention is directed to a device having an arm and a sensor that can differentiate two events. The arm is pivotally mounted to move in different directions upon the occurrence of different events. A section of the arm includes a trigger section having an unequal distribution of a sensed characteristic. A first event moves the arm in a first direction that is sensed by the sensor in a first manner. A second event moves the arm in a second direction that is sensed by the sensor in a second manner. The sensor signals a controller that oversees the image forming process. Methods of operating the arm and sensor are disclosed for detecting the two separate events, and signaling the controller accordingly.