An agricultural baler includes a main bale chamber having a pair of opposed side walls, with each said side wall including a plunger slot arrangement defining a plunger slot. A pair of plunger slot rails are positioned in each plunger slot, including a top rail positioned at a top of a respective plunger slot and a bottom rail positioned at a bottom of a respective plunger slot. A plunger is reciprocally disposed within the main bale chamber. The plunger includes a pair of opposed sides and at least one roller extending laterally outward from each side, with each roller being positioned within a respective plunger slot. The baler is characterized by a pair of plunger slot cover assemblies, with each cover assembly being associated with a respective plunger slot and having an upper cover and a lower cover.
