PR 307 Sound Problem

Hello,
I hope anyone of you can help me with my problem.
I own a PR307 and a couple of weeks since a couple of weeks the sound it makes is very distorted.
The Grand Piano sounds more like a distorted guitar. (but not only the grand piano, but all the sounds (also the rhythms))
When I plug in my headphones, I hear the same distorted sounds...
Is this fix-able?

Another problem is the "TEMPO¨/PROGRAMM-dial" (turning knob) doesn't respond well.
Is this also fix-able?

Thanks a lot!

Best regards,
Coen