Right Speaker on Lenovo ThinkCentre A60 Headset not working

I have a Lenovo ThinkCentre A60 headset. Recently, the foam ear comforters on the headset wore off and flaked off. I used the headset without them for a while, but then I remembered I had another spare headset with cloth ear rings that I could take off and put on the A60. So I put the foam ear comforters on the headset, and it was great for a while. I could tell that the ear rings were putting stress on the speakers, but I didn't think it would be anything bad. After about an hour, the left speaker (the one farthest from the microphone) stopped working. No sound comes out of it, at all. How do I fix this?