Abstract: A moving-web slack reducing system including a deformable tension roller, such as a brush-type tension roller having an outer surface defined by the ends of a plurality of bristles. The slack reducing system may be deployed in a preheater assembly for a machine for manufacturing corrugated board. The bristles of the deformable tension roller allow the outer surface of the tension roller to deflect both radially and in the cross-machine direction without binding to the paper web. The bristles may also deflect variably across the tension roller in the cross-machine direction. Thus, the deflection of the bristles adjusts automatically and virtually instantaneously to changes in the tension of the paper web to compensate for variations in tension across the web in the cross-machine direction. This allows the brush-type tension roller to take the slack out of the paper web without having to rapidly and precisely adjust any actuators.