if it is a bearing, probably not worthwhile. generaly the seal goes before the bearing gets bad enough to make a racket. then you get water into the motor and start corroding everything and making a mess.
but , more likely it is just a piece of gristle or bone or plastic caught in the grinding mechanism. some of that stuff will last an amazingly long time but it will eventualy wear off or come loose and get ground up. grinding up a bucket of ice cubes will sometimes speed up the process.
another possibility is that part of the grinding mechanism is bent or worn so that it comes in contact with the wall of the grinding chamber(not likely, but possible).