I think the problem may be that the cue ball of the Centennial set (Blue Circle IIRC) is supposed to be made in the same batch and precision matched to the rest of the object balls.
This is apparently one of the few non-cosmetic differences between the Centennials and the Aramith Super Pros, which use either the Aramith Logo or Pro Cup cue balls.
You may want to trawl Ebay to see if anyone is selling one there, or try calling Brunswick directly, they are usually quite responsive to customer questions.