I recently purchased a 1993 850 GLT. In the trunk there is a Volvo 6-Disc changer that the preivious owner said came with the car. At first the CD player worked every now and then, but now it won't work at all. I know I am putting the discs in correctly, but on the screen in the dashbboard it just skips over every disc like it would if there weren't any in there. I can hear the discs changing as it cycles through them, but they don't play. Is there anything I can do to fix it? All the visible wires seem to be properly connected. How can I check the other wires?