A duct for conveying influent to a head cell having multiple, vertically aligned trays has an inlet end and an outlet end. An electronic circuit stores an indication of the amount of toner remaining, and a value controlling a voltage applied to at least one of the electrical development components. A spacer is preferably attached to an underside of the base for keeping the base at a level above ground. These fairings are connected to the ends of a front transverse wing which extends from both sides of the nose of the central body and which is profiled so as to generate a negative lift during movement.