Velodyne FS12 Subwoofer Problem. My Velodyne sub has worked perfectly for several years. I just

Question

My Velodyne sub has worked perfectly for several years. I just moved to a new home and set up my home theater system. When I turn on the sub there is a loud hiss coming from the speaker. I already have a Mondial Magic on the incoming cable line so that is not the problem. I have disconnected the rca cables from the sub and the hiss is still there with only the sub plugged into the wall. Additionally the sub thumps when I turn it off. It is already set to the auto position. Is the subwoofer bad??? Am I missing something??? Please help if possible....