Back when I was restoring ZONKEY I found that the ball bearings were in pretty bad shape and set out to find a set. This may be of help:
http://home.earthlink.net/~rlbpantera/rack/
Fortunately at the time Larry Stock had some in stock and I bought a set. I don't know if he still does but it's worth a try. None of the other venders did.
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