ZMX52 : No output

No output. My ZMX52 is not working. On power up the LEDs flash. The peak LEDs on channels 2/3 and 4/5 stay lit. The power led does not light. All channels have been tested with a 1khz sine wave. There is no output, just a faint click as the level pots pass the centre detent. Does anyone have a service manual or circuit diagram? It would be possible to reverse engineer the circuit but it's a lot of work on a cheap mixer
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