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...that original headset doesn't owe you anything more. I have always had the best luck with replacing entire headsets as a unit, like that Tange you mention in your original post. There are people on very tight budgets who root around in the parts drawers over at the co-op, and bodge something together. Some of those seem to work better than others. It's a bad idea to simply grab a different crown race and assume it will have a similar bearing surface curve to your original, and will work with it.

But it is possible to replace the crown race and the lower head tube race, along with the bearings that fit, as a unit. I just don't think it's worth the added trouble.