Yamaha Clavinova CLP-560 will not play
I have a Yamaha Clavinova CLP560 approx 16 years old. It powers up OK but does not play. Default LEDs appear at power-up. Pressing buttons causes correct selection of functions (as indicated by LEDs); however if any key is depressed button selections no longer operate (stays frozen at last selection). All fuses are OK. Voltages to main board look OK (+5 and +12). No sign of power supply problems or visible damage to any parts. Any suggestions appreciated, including where to download free a service manual.