We have found that the wires inside the white ribbon-cable may break in time from wear. The wires tend to break at the blue end of the cable where it enters the carriage PC board.
If you are experiencing this problem there is a solution. When installing the cable bend it around the carriage PCB using foam strips as indicated below. To do so you'll need to first remove the two (2) lower screws of the carraige PCB.
