Embodiments of the present invention provide a process that monitors a magnetic playback signal while gradually increasing an electricity supply amount for a heater to thereby determine contact between a magnetic head slider and a magnetic disk medium. In some aspects, an escapement assembly includes a sensor system configured to detect a target item of a plurality of items on a feed conveyor of a conveyor system. The device provides unique, repeatable test conditions leading to a rollover as well as during the rollover.