We recently acquired a model HGS-10 GB in non-working order. We found a blown fuse, which we replaced with the correct 12A Slo-Blow. The sub now powers up, however it is giving some feedback with no input hooked up, and with input the sound quality is poor and intermittent. We checked the driver and noticed that the cone does not move at all front or back when carefully pressed on. Should the cone move like a standard subwoofer or is this normal for the unit? Also, we measured the DC resistance of the driver and got 2.5 Ohms. Is this correct? Please let me know what the problem might be, as we would really like to see what this first class subwoofer is capable of. Thank you for your time.