I just bought a 91 with the Bose system. The rt rear speaker has a very loud static "crack" everytime I hit a bump. When parked the Rt speaker sounds like it's blown. The left rear speaker was dead and I found it to be disconnected. Obviously the seller was hiding a problem. Both speakers look fine and the radio plays fine from the front speakers. Is this a problem with the radio or wiring or a circuit board someplace? Thanks for the help.