An automated checkout system for reading optical data, such as barcode labels, on a bottom surface of an item using a data reader. The automated checkout system includes a housing supporting a leading conveyor section and a trailing conveyor section separated by a gap. The housing movably supports a transition element positioned across the gap for helping items transition between the conveyor sections. The transition element is movable between a first position and a second position. A sensor is in communication with the transition element and is configured to sense the position of the transition element, where movement of the transition element from the first position to the second position activates the sensor. When activated, the sensor may send a signal to a terminal to display a warning message to a user. Alternatively, the sensor may send a signal to an automatic shut-off mechanism to stop operation of the conveyors.