A cutter device for an agricultural harvester, comprising: a rotor with a plurality of tines, wherein the rotor is rotatable to transfer an agricultural crop along a feed path; a knife, wherein the position of the knife is adjustable; a bottom plate located beneath the rotor, wherein the feed path is located between the rotor and the bottom plate, and the bottom plate includes an opening through which the knife extends at least when in a cutting position; a control mechanism including a control element which is movable between at least a primary position and a secondary position, wherein the control element is arranged to control movement of the knife between • a first position in which the knife is in a cutting position in the feed path, • a second position in which the knife is substantially out of the feed path in a non-cutting position, and • a third position in which the knife is located at an intermediate position between the cutting position and the non-cutting position, wherein the control mechanism is arranged such that, in a condition wherein the control element is in the secondary position, the knife is in, or may freely move to, the second position of the knife, and wherein the control mechanism includes a selection mechanism that is arranged to select between first and second selection configurations, wherein • in the first selection configuration, in response to the control element being actuated to move from the secondary position to the primary position, the control mechanism is arranged to move the knife from the second position to the first position, and • in the second selection configuration, in response to the control element being actuated, the control mechanism is arranged to move the knife from the second position to the third position during movement of the control element from the secondary position to the primary position, and in a condition wherein the control element reaches the primary position, the knife is freely movable to return to the second position of the knife. a rotor with a plurality of tines, wherein the rotor is rotatable to transfer an agricultural crop along a feed path; a knife, wherein the position of the knife is adjustable; a bottom plate located beneath the rotor, wherein the feed path is located between the rotor and the bottom plate, and the bottom plate includes an opening through which the knife extends at least when in a cutting position; a control mechanism including a control element which is movable between at least a primary position and a secondary position, wherein the control element is arranged to control movement of the knife between • a first position in which the knife is in a cutting position in the feed path, • a second position in which the knife is substantially out of the feed path in a non-cutting position, and • a third position in which the knife is located at an intermediate position between the cutting position and the non-cutting position, • a first position in which the knife is in a cutting position in the feed path, • a second position in which the knife is substantially out of the feed path in a non-cutting position, and • a third position in which the knife is located at an intermediate position between the cutting position and the non-cutting position, wherein the control mechanism is arranged such that, in a condition wherein the control element is in the secondary position, the knife is in, or may freely move to, the second position of the knife, and wherein the control mechanism includes a selection mechanism that is arranged to select between first and second selection configurations, wherein • in the first selection configuration, in response to the control element being actuated to move from the secondary position to the primary position, the control mechanism is arranged to move the knife from the second position to the first position, and • in the second selection configuration, in response to the control element being actuated, the control mechanism is arranged to move the knife from the second position to the third position during movement of the control element from the secondary position to the primary position, and in a condition wherein the control element reaches the primary position, the knife is freely movable to return to the second position of the knife. • in the first selection configuration, in response to the control element being actuated to move from the secondary position to the primary position, the control mechanism is arranged to move the knife from the second position to the first position, and • in the second selection configuration, in response to the control element being actuated, the control mechanism is arranged to move the knife from the second position to the third position during movement of the control element from the secondary position to the primary position, and in a condition wherein the control element reaches the primary position, the knife is freely movable to return to the second position of the knife.