No sound coming out of the right speaker on Yamaha CLP 990
I have a Yamaha CLP-990 that I purchased in 2003. About two weeks ago, sound stopped coming out of the right speaker. When I plug in headphones, no sound comes through the right earpiece, either. When I put my ear up against the right speaker, I can hear faint white noise that sounds the same as the white noise coming out of the left speaker. I made sure the plug is connected tightly. I haven't taken anything apart, but instead, I am hoping you can shed some light on my problem. Thank you!