The mystery has been solved! Several months ago, we posted about a set of mystery tubes made of brass that ended up proving themselves useful to repair the seconds counter hand for a vintage chronograph movement. As it so happens, those mystery tubes are actually bushing wire, and hail from a time when zero and low jewelled mechanical watches were more commonplace.
The bushing wire was used to fabricate custom-tailored replacement bushings (also sometimes called bearings) in a watch or clock where the pivots had worn away at the original bearing surface. As most unjeweled bearing surfaces in watches today are either rhodium plated or plastic, the need for repairs requiring bushing wire has fallen out of the norm. However, bushing wire still holds its place in the workshop that undertakes the restoration and repair of vintage timepieces.