Static in right speaker and low volume in left speaker.

Hi. My father has a Casio CTK-3000 which he has owned for a few years. He turned it on today for th first time in several months and now there is static in the right speaker and low volume on the left speaker. We've tried connecting to an amp and the static is still there. We have even tried plugging it into a different outlet and still the same result. While it was not being used, it was covered.

Does anyone have any ideas what might be causing this. Thank you.