Except Belkin in their infinite wisdom have declared it to have no user serviceable parts inside, and have enforced this by using tamper-proof one-way screws on it that are supposedly impossible to undo with an ordinary screwdriver, or indeed with any screwdriver.
Not that they were particularly effective at stopping me.
Of course, it turned out that the rattling piece was just a bit of plastic that had presumably snapped off something or other. Still, better that than a bit of metal waiting to let the magic smoke escape.