the ball should have some movement in it. the ball just rests on the rollers, the case is there to keep it in.
the chatter should be fine. the rollers have a burnished section on them that grips the ball pretty hard. they eventually wear down. Also, once the ball and rollers get a layer of dirt and oil on it from being used, the chatter should subside.
After a good clean, I normally apply a bit of silicone spray to a papertowel and give the ball a super light coat. not much, or enough to attract additional dirt... but just enough to allow the ball to slip over the rollers easier.during normal operation the ball has to skid on a bias on the rollers, squeaky clean ball and rollers don't like to do this.