I bought these Klipsch Promedia 2.1s from ebay used where the dude said they are in working order. I buy them, set them up, and only the subwoofer and one speaker works.... weird. I switch the speakers. Now the other speaker works. Defective subwoofer? Any suggestions? Is it the way I am connecting it to the subwoofer or something? Last time I buy from ebay again. Seller had 99.9% positive feedback.