Hi All,  I've had two experiences with soldering in 'extra' nipples
to a trackerbar.  In both cases, it was an auto-sustain hole that was
added, so it was away from the main note nipples.  Still, the immediate
problems were (a) getting the area cleaned and fluxed so the solder
would stick quickly (b) tinning the nipple to be installed prior to
installing it, and (c) applying the heat fast enough to melt the solder
without melting the solder by the note nipples.

I employed a large heat sink (a vise with beveled aluminum pieces to
secure the bar in the vise without scratching it), and a mini propane
blow torch (which I bought specifically for the job).  The job went
pretty smoothly even though I could see that the solder around the
closest note nipples was getting 'soft'.

I considered what I might do if I ever had to replace a broken nipple
within the area of note nipples, and decided that some sort of a jig
would have to be made to hold all of the surrounding nipples stationary
as the remains of the offending nipple were removed and the new (or
more accurately, a used one from another bar that was dismantled for
the purpose at hand) nipple was soldered in place.  I figured there
would be a pretty good chance that some of the solder would 'leak' into
the empty hole, but also envisioned that a good round toothpick, shoved
into the hole from the front-side of the bar, would be adequate to
reduce or eliminate that problem.

The real challenge, it seemed, was making the jig to hold all the other
nipples in place AND still give me enough room to work down in such a
tiny space.  Fortunately, I've never had to actually do the job, and
certainly don't envy anyone who has faced the challenge.

Musically,
John A Tuttle
Player-Care.com