Originally Posted by LóFarkas
Don't just adjust it. Take it apart, clean, and reassemble with new grease (you have grease, right?). Take a good look at the stuff inside to see if it's worn.
Since it is a cartridge bearing hub, there's not really anything inside. Just adjust it. If it doesn't turn smoothly without wobbling (being horribly loose), then you need new bearings. But that's probably not the case, those things last forever.