I have a 99 C70 HT Coupe with the SC-901 premium sound system. How can I tell if my center speaker is functioning properly. I turn up the volume on it and don't hear anything. Do I need to use a different CD or something? If it is determined that it's not functioning properly, how do I get the grill off of it to replace it. I love this car but I'm staring to get frustrated. Please help!!!!