A cutter device for an agricultural harvester, comprising: a rotor (42) with a plurality of tines (48), wherein the rotor (42) is rotatable to transfer an agricultural crop along a feed path; a knife (56), wherein the position of the knife is adjustable; a bottom plate (60) located beneath the rotor (42), wherein the feed path is located between the rotor (42) and the bottom plate (60), and the bottom plate (60) includes an opening through which the knife (56) extends at least when in a cutting position; a control mechanism (80) including a control element (82) which is movable between at least a primary position (C1) and a secondary position (C2), wherein the control element (82) is arranged to control movement of the knife (56) between a first position in which the knife is in a cutting position (C) in the feed path, a second position (N) in which the knife is substantially out of the feed path in a non-cutting position, and a third position in which the knife (56) is located at an intermediate position between the cutting position (C) and the non-cutting position (N), wherein the control mechanism (80) is arranged such that, in a condition wherein the control element (82) is in the secondary position (C2), the knife (56) is in, or may freely move to, the second position (N) of the knife, and wherein the control mechanism (80) includes a selection mechanism (92) that is arranged to select between first and second selection configurations, wherein in the first selection configuration, in response to the control element (82) being actuated to move from the secondary position (C2) to the primary position (C1), the control mechanism (80) is arranged to move the knife (56) from the second position (N) to the first position (C), and in the second selection configuration, in response to the control element (82) being actuated, the control mechanism (80) is arranged to move the knife (56) from the second position (N) to the third position during movement of the control element (82) from the secondary position (C2) to the primary position (C1), and in a condition wherein the control element (C2) reaches the primary position (C1), the knife (56) is freely movable to return to the second position (N) of the knife.