Rockster

Today my rear right channel went out on my sub. I can very faintly hear sound out of the speaker. I have tried different wires and speakers on the same channel without success, but all the speakers work on the other 3 channels. I did not open the sub, afraid of voiding my warranty, and I emailed Klipsch about the problem. I bought the speakers the 25th of April so they should be under warranty. I will call Klipsch tommorow and try to get a RMA. Does anyone else have any suggestions or steps I may have missed? Thanks!