Abstract: A method and apparatus for preventing jams in a carton coding machine or the like are disclosed. The apparatus includes a pivotally mounted coding assembly actuated by a cylinder and cooperating solenoid operated directional control valve. A photo transceiver and reflector are provided for detecting a change in article flow, such as is caused by a defective article or article jam. Control means, responsive to a detected defective article or article jam, substantially simultaneously interrupts power to the coding assembly and displaces the coding assembly from the path of the articles. This prevents the defective article from wedging in the coding assembly and jamming the machine. After a delay period, the coding assembly is returned to the operative position for coding the following articles.