Loss of sound - PX-S3000

[Bobbo]

It's been many months since the last time this happened, but today it happened again:  the sound suddenly went out on the internal speakers while I was playing the instrument.  Or rather, about 98 percent of the sound went out -- very faint tones were still being produced.  This time, though, I was also using external amplification and speakers through the audio out jacks, and their sound was unaffected.  Also, the S3000 volume control continued to regulate the external sound level as usual.  I'm wondering if this additional information helps anyone get more insight into what the exact anomaly might be that is causing this intermittent problem.