Abstract: An apparatus for measuring the deflection of a belt in an electrophotographic printing machine includes an elongate arm member having a first end and a second end. The second end engages and is displaced by the belt. A gearbox includes a plurality of gears interconnected into a gear arrangement, and a gearbox shaft rotatable by the gear arrangement. The second end of the arm member is coupled to the gear arrangement, which converts displacement of the second end of the arm member to rotation of the gearbox shaft. An encoder is associated with the gearbox shaft. The encoder includes at least one encoder output. The encoder senses rotation of the gearbox shaft and issues electrical pulses on the encoder output. The electrical pulses are indicative of the magnitude and direction of the rotation of the gearbox shaft. A counter includes at least one counter input and at least one counter output. The counter input is electrically connected to the encoder output.