After printing or feeding several labels: If the media does not track down the center (moves from side to side) or the sides of the media (liner, tag, paper, etc.) are frayed or damaged when exiting the printer, the media guides may need further adjustment.
If this does not correct the problem, the media can be routed over the two roll-holding pins on the media guide. An empty roll core of the same width as the stack of the fanfold media can be placed between the roll holders to provide additional support for thin media.