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One possible source of the problem would be if taps were too oversize. Bottom bracket tap manufacturers intentionally make their taps slightly oversize in order to accommodate manufacturing tolerances.
Years ago I replaced a VAR tap set I had been using with a Bicycle Research one only to find that cups really rattled around in there something fierce. I asked the manufacturer about it and they told me how many thousandths they were purposely made oversize because Campag was putting out some cups which were too large for shells which had been tapped with Campag taps.
I replaced the BR set as soon as possible.
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