Kurzweil pc88 sound cuts out

I had this same problem. Pressing the panic button restored full volume, but again only for some seconds. I went to the 'midiscope' feature (in the global menu) to show any midi control messages that could be the cause. Indeed, it showed midi control message with volume, even though I did not touch any controls and no external midi devices were connnected. The midi scope in my case showed message was coming from midi channel 1, controller 11, which didn't mean much to me. I moved all knobs and sliders, like the pitch wheel and volume sliders and saw similar messages in the midiscope, but all on different controller numbers, not #11. Then I thought it could be coming from the external controller connectors on the back. I connected a foot pedal to them and found #11. With finding it, and by doing so, maybe cleaning or moving something in the plug connector, the problem disappeared and did never reapper.