Speakers randomly begin to not work

I assume the answer to this is "it's just dying," but here it goes anyway. I have a Yamaha htr-5840 receiver that I got open-box. When I got it, one of two sets of front speaker outputs didn't work, but I didn't care because I only have one set of front speakers. I've had it for over 2 years, but just recently, the front and rear speakers have stopped working simultaneously, leaving the center and centerback speakers as the only ones going. Has anyone encountered a similar problem?


Also, everything is connected correctly, and the speakers work when plugged into another source. Nothing changed or shifted, they simply stopped working.