A crop cutting device for an agricultural harvester comprising: a crop guiding surface, a plurality of substantially parallel knives mounted below the crop guiding surface and aligned with respective slots in the crop guiding surface, the knives being movable between a retracted inoperative position below the crop guiding surface and an extended operative position wherein at least a portion of a cutting edge of the knives projects above the crop guiding surface, and an actuating mechanism for moving the knives between the retracted inoperative position and the extended operative position, the actuating mechanism comprising a plurality of movable operating members, associated with respective ones of the plurality of knives and movable from a first position in which the knives are in the retracted inoperative position, to a second position in which the knives are in the extended operative position, a support frame configured to hold the operating members in a sliding relation to the support frame, and an actuator coupled to the support frame for moving the support frame between an employed position and a retracted position, the employed position being closer to the knives than the retracted position, characterized by a knife insert assistant that is coupled to the support frame and configured for blocking a sliding movement of the operating members relative to the support frame during a movement of the support frame from the retracted position to the employed position. a crop guiding surface, a plurality of substantially parallel knives mounted below the crop guiding surface and aligned with respective slots in the crop guiding surface, the knives being movable between a retracted inoperative position below the crop guiding surface and an extended operative position wherein at least a portion of a cutting edge of the knives projects above the crop guiding surface, and an actuating mechanism for moving the knives between the retracted inoperative position and the extended operative position, the actuating mechanism comprising a plurality of movable operating members, associated with respective ones of the plurality of knives and movable from a first position in which the knives are in the retracted inoperative position, to a second position in which the knives are in the extended operative position, a support frame configured to hold the operating members in a sliding relation to the support frame, and an actuator coupled to the support frame for moving the support frame between an employed position and a retracted position, the employed position being closer to the knives than the retracted position, a plurality of movable operating members, associated with respective ones of the plurality of knives and movable from a first position in which the knives are in the retracted inoperative position, to a second position in which the knives are in the extended operative position, a support frame configured to hold the operating members in a sliding relation to the support frame, and an actuator coupled to the support frame for moving the support frame between an employed position and a retracted position, the employed position being closer to the knives than the retracted position,