Abstract: A gaming device is provided with detectors configured to substantially reduce the potential for unauthorized manipulation of a coin output system. A pair of detectors can be used to output an error signal when the sequence or timing of detector blockages departs from that which would be expected from normal coin movement. A second optical detector is configured to provide a signal used to output an error signal when the second detector detects radiation or light during a time that a first detector is also detecting light from a paired radiation source. An error signal is preferably output when an optical detector is blocked for a period of time which exceeds a maximum blockage threshold, and preferably the threshold may be dynamically adjusted.