Paul Jones

I have a powered Klipsch 15” sub and it also started humming about 5 years ago. It hums with or without inputs attached. I’ve tried multiple circuits in the house and it still hums. I pulled out the amp and nothing is loose or visibly damaged. Is there anything I can do or should I by Yamaha or JBL? Can I add a ground somewhere? I’ve called around and no one works on them. At $2000 I hate to throw it away...