I don't think that's the issue. It sounds like he clipped the wire going directly to the driver. Not sure now you go about doing that, but it sounds like you either need a new driver, deal with one working headphone, or... ummm... Mcguyver it? Maybe you could buy a spare driver from Sennheiser? Or do a HD25 to Amperior transplant and basically create your own custom pair of HD-25 Aluminum.