A print media loading mechanism for a modular printer assembly is disclosed. A pair of opposed endless belts is provided. Each belt passes around a pair of rollers. Opposed roller pairs are slidably received by sliders attached to a frame of the printer assembly. A pair of arms is attached to each opposed roller pair, the pair of arms having a common pivot point. A traversing mechanism connects to each pair of arms at the common pivot point. A drive assembly, including at least one worm screw and motor which rotates the worm screw, is also provided. The worm screw interacts with the traversing mechanism in order to move the traversing mechanisms apart and closer together respectively. This in turn moves the opposed endless belts apart and closer together respectively.