For years I would remove the tracker bar with the tubing cut short
and put it in a PVE [pipe cylinder] wide enough to accommodate any
I might run across.  The bottom cap was glued on and the top was
removable.  I filled it with ammonia which not only made the tubing
drop off but after two days at the longest, it cleaned a black tracker
bar to the point it only needs a final buffing.

Also, someone was asking how to remove the "cement" at the tracker
bar nipples.  I used the same PVE tube but poured in denatured alcohol.
Sometimes it would take a few days to do the job, but then it would
fall off with little effort.

The "cement" is actually burnt shellac, in those days a great sealant
for wood to metal and used in the tracker bar to seal the lead joint.

Bruce Mercer