A timber-working head and method of operation are provided. The head has a frame to which first and second arms are pivotally connected. Respective linear drive actuators pivot the respective arms relative to the frame to open and close them. At least one processor controls application of pressure by the linear drive actuators such that the arms grasp timber to be processed by the head. The position of the linear actuators is used to determine whether the timber is offset from a feed axis of the frame beyond a predetermined distance, and the application of pressure by one of the linear actuators to reduce the offset to be within the predetermined distance.
