An agricultural system comprising: an agricultural baler, comprising: a bale chamber partly defined by at least one movable density door (210A, 210B, 210C); at least one actuator (220A, 220B) for moving the at least one density door (210A, 210B, 210C); and a rotary input shaft connected by way of a baler driveline to a rotatable flywheel, the driveline including a transmission for controllably transferring rotary drive between the input shaft and the flywheel, wherein the transmission has an output shaft; characterized by a control unit configured to: receive a start-up-routine-trigger-signal; receive an output-shaft-speed signal that is representative of a rotational speed of the output shaft; in response to receiving the start-up-routine-trigger-signal, compare the output-shaft-speed signal with one or more threshold-conditions, and if the output-shaft-speed signal does not satisfy at least one of the threshold-conditions, then: determine an actuator-control-signal for causing the at least one actuator (220A, 220B) to move the at least one density door (210A, 210B, 210C) in order to enlarge the bale chamber; and provide the actuator-control-signal to a drive system for driving the at least one actuator (220A, 220B); wherein the control unit is configured to stop comparing the output-shaft-speed signal with the one or more threshold-conditions after a start-up-duration period of time. an agricultural baler, comprising: a bale chamber partly defined by at least one movable density door (210A, 210B, 210C); at least one actuator (220A, 220B) for moving the at least one density door (210A, 210B, 210C); and a rotary input shaft connected by way of a baler driveline to a rotatable flywheel, the driveline including a transmission for controllably transferring rotary drive between the input shaft and the flywheel, wherein the transmission has an output shaft; characterized by a bale chamber partly defined by at least one movable density door (210A, 210B, 210C); at least one actuator (220A, 220B) for moving the at least one density door (210A, 210B, 210C); and a rotary input shaft connected by way of a baler driveline to a rotatable flywheel, the driveline including a transmission for controllably transferring rotary drive between the input shaft and the flywheel, wherein the transmission has an output shaft; characterized by a control unit configured to: receive a start-up-routine-trigger-signal; receive an output-shaft-speed signal that is representative of a rotational speed of the output shaft; in response to receiving the start-up-routine-trigger-signal, compare the output-shaft-speed signal with one or more threshold-conditions, and if the output-shaft-speed signal does not satisfy at least one of the threshold-conditions, then: determine an actuator-control-signal for causing the at least one actuator (220A, 220B) to move the at least one density door (210A, 210B, 210C) in order to enlarge the bale chamber; and provide the actuator-control-signal to a drive system for driving the at least one actuator (220A, 220B); wherein the control unit is configured to stop comparing the output-shaft-speed signal with the one or more threshold-conditions after a start-up-duration period of time. receive a start-up-routine-trigger-signal; receive an output-shaft-speed signal that is representative of a rotational speed of the output shaft; in response to receiving the start-up-routine-trigger-signal, compare the output-shaft-speed signal with one or more threshold-conditions, and if the output-shaft-speed signal does not satisfy at least one of the threshold-conditions, then: determine an actuator-control-signal for causing the at least one actuator (220A, 220B) to move the at least one density door (210A, 210B, 210C) in order to enlarge the bale chamber; and provide the actuator-control-signal to a drive system for driving the at least one actuator (220A, 220B); wherein the control unit is configured to stop comparing the output-shaft-speed signal with the one or more threshold-conditions after a start-up-duration period of time. determine an actuator-control-signal for causing the at least one actuator (220A, 220B) to move the at least one density door (210A, 210B, 210C) in order to enlarge the bale chamber; and provide the actuator-control-signal to a drive system for driving the at least one actuator (220A, 220B); wherein the control unit is configured to stop comparing the output-shaft-speed signal with the one or more threshold-conditions after a start-up-duration period of time.