I have a 2002 Passat with factory Monsoon system. Lately the volume on the driver's side speakers - front and back, I think - gets quiet for several seconds. It's very obvious when I turn the balance all the way to one side and then the other. It spontaneously comes back to normal. It happens once every 5-10 minutes. I disconnected and then reconnected the plugs to the amp, but I'm still having the problem. Any ideas?