Bryan Gallagher sounds like either the crossover cable has a short in it or some connection on the driver (speaker) has come loose. This teardown [guide|54520] should help you getting to the connections. Check for anything abnormal looking. If unsure post some pictures of what you find with your QUESTION [guide|21499]
That way we can see what you see. Remember the reason for iFixit to host this forum is to keep devices out of the landfill and to empower everyone to repair their own devices. So keep on repairing away; Repair is Noble