Logitech Z-560 Computer Speakers "repair z2300" Questions

Z2300 system works fine. Tried replugging the wires, jiggling switches, tapping on the heat sink, even pulled the electronics (joy!) and reseated the connections. Everything on the amp pcb looked fine

...repair for Logitech Z2300 speaker system? The yellow input to the amp doesn't work - both speakers will work in the other input Contact Logitech - their information is here: ...