My neighbor has recently "upgraded" to a surround sound system, and in the process gave me his Altec Lansing 846Bs. The walnut cabinets are in magnificent shape and the woofers appear to be working fine. Having said that, I have two questions. There is no output from either of the horns. He said they both appeared to go out at the same time. What is the most likely culprit, the driver or the crossover, and in either case, what is the easiest way to get the grill covers off without damaging the cabinet or fabric? He replaced the fabric several years ago, and indicated the grills are just held in place by fricition. Thanks in advance for your help.