That seems to make a lot of sense Allen. One might consider too that the repeated use could have a buffing or burnishing effect on the surface of the old pins at a microscopic level, such as to make them more "slippy". Doubtless there are engineering instruments that can measure friction on the surface of a rod of small diameter! Teflon powder, after all, makes surfaces more slippy with a microscopically thin molecular layer not measurable by a micrometer. Best, David. "I carefully mic'd just the ends of many of the old pins and found them to be a half-thousandth smaller (50.5 rather than 51). So my operating theory at this point (until someone convinces me I'm wrong) is that indeed (as my shop mate - and also Wim Blees in an earlier post - suggested) the pins themselves have worn slightly. At first this seems unlikely; but then again, after 70+ years of wear, perhaps it's not surprising that some wear would take place due to the friction from the bushing cloth turning hundreds of thousands of times? "
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