I have a Yamaha DGX-650 digital piano. The 1/4 inch output audio jack abruptly stopped working. I had been using it for my headphones as well as a Yamaha 400S stagepas. I have contacted Yamaha and they've given me the name/number of a local repair tech. Unfortunately, that repair tech has an answering service and has never once responded despite leaving simple messages. I hate to throw the piano out because it functions fine otherwise, except for the audio jack. Anyone out there know if this is a repairable item or know the electrical schematics to open the cabinet and potentially repair this myself or get an electrical tech. Thanks in advance.