Cambridge Megaworks 510D problems

Hi, I bought off eBay a few months ago some Cambridge Megaworks 510D and the other night I had them on loud for a long period of time then they stopped working! I tapped the main sub unit and it work for a bit apart from when the volume was up loud. However now even now when I tap it doesn’t work just get some static through the speakers. I think it’s a loose but I don’t know where to look any suggestions I would be grateful.
 
Yeah I'm guessing the guy off eBay bought them back off Creative and has fixed that problem and sold them on to me. So unfortunately I can’t send them back! Thanks
 
Back