Method for preventing or removing a plugging of a feeder duct of a baler, said baler comprising: - a bale chamber having an inlet opening formed therein; - a feeder duct communicating with the bale chamber through the inlet opening for charges of crop material to be transferred from the feeder duct into the bale chamber, wherein the bale chamber has a bottom wall in which the inlet opening is formed, and wherein the feeder duct has an upper end facing generally upwardly and communicating with the inlet opening in the bale chamber and a lower end facing generally in a forward direction; - a plunger reciprocable within the bale chamber to compress successive charges of crop material received from the feeder duct to form a bale; - feeder means operable within the feeder duct to accumulate a charge of crop material therein and then stuff that accumulated charge into the bale chamber; wherein - the feeder duct has a top wall and a bottom wall extending between the lower end and the upper end of the feeder duct, said top wall providing an upper boundary of the feeder duct and said bottom wall providing a lower boundary of the feeder duct; the method comprises: - increasing the distance between the top wall and the bottom wall of the feeder duct in at least a part of the feeder duct, while leaving the upper boundary provided by the top wall of the feeder duct and the lower boundary provided by the bottom wall of the feeder duct intact, and causing the feeder means to operate in the feeder duct with the increased distance between the top wall and the bottom wall; characterised in that the method further comprises monitoring the crop pressure in the feeder duct as a function of the location along the length of the feeder duct, and increasing the distance between the top wall and the bottom wall of the feeder duct in at least the part of the feeder duct where the crop pressure exceeds a predetermined pressure, wherein preferably the distance between the top wall and the bottom wall of the feeder duct is additionally increased in the part of the feeder duct downstream of the part where the crop pressure exceeds a predetermined pressure. - a bale chamber having an inlet opening formed therein; - a feeder duct communicating with the bale chamber through the inlet opening for charges of crop material to be transferred from the feeder duct into the bale chamber, wherein the bale chamber has a bottom wall in which the inlet opening is formed, and wherein the feeder duct has an upper end facing generally upwardly and communicating with the inlet opening in the bale chamber and a lower end facing generally in a forward direction; - a plunger reciprocable within the bale chamber to compress successive charges of crop material received from the feeder duct to form a bale; - feeder means operable within the feeder duct to accumulate a charge of crop material therein and then stuff that accumulated charge into the bale chamber; - the feeder duct has a top wall and a bottom wall extending between the lower end and the upper end of the feeder duct, said top wall providing an upper boundary of the feeder duct and said bottom wall providing a lower boundary of the feeder duct; - increasing the distance between the top wall and the bottom wall of the feeder duct in at least a part of the feeder duct, while leaving the upper boundary provided by the top wall of the feeder duct and the lower boundary provided by the bottom wall of the feeder duct intact, and causing the feeder means to operate in the feeder duct with the increased distance between the top wall and the bottom wall;