A wall-hanging-aid device comprises four retractable tape measures encased in a housing and at least one template for aligning a hanging position or hooking position of an object on a vertical surface, such as a picture on a wall. In one embodiment, an apparatus includes at least one elongated member adapted to be positioned proximate to a surface of a work piece. To accomplish Hall effect sensing, an electric current carrier is situated to interact with the magnet for production of Hall voltage which is monitored by a voltage sensor in communication with a controller that regulates motor speed in accord with Hall-effect sensed need through pulse width modulation in response to the voltage value according to proportional integral derivative methodology. In addition, the valve body acts to seal the interior space of the frame from invasion by dust via the through-hole when the carriage fixing screw is removed from the through-hole and normal scanning operation of the image-reading apparatus is resumed at the new location.