Please forgive the correction to Mr. Kinsler's note, but there are
a couple of mistakes in his posting that could lead to destruction of
a musical box comb rather than its repair

Let's start out with the basics: If we are talking about a modern
musical box mechanism made by Sankyo or Reuge, they may be able to
supply a replacement or maybe not; to be perfectly honest, I don't
really care.  If you're talking about replacing a comb from an antique
musical box, then the answer is no, you cannot find a replacement comb
-- unless you're talking about a Polyphon, Regina, Stella or the like,
in which case you might be able to find a replacement from a similar
mechanism that was destroyed at some point in time.

I've never tried silver solder but I understand that it melts at very
high temperature; this is problematic for musical boxes and I'll
explain why.  The comb is soldered to the (usually brass) frame using
regular [tin-lead] solder.  If you heat the comb too much you'll melt
that solder and it will slide right off.  The same is true for the
resonators (or lead weights underneath the bass teeth).  You also run
the risk of removing the temper from the comb and you will have merely
a piece of steel.

Thus you want to use "soft" solder to attach.  I use TIX solder as it
has a reputation of being stronger.

Now that we've attached the tooth, I'd like to take it back one step.
If we harden and blue the tooth after it's attached, we are sure to
ruin everything!  To harden the tooth you need to get it to red-hot,
then throw it into water/oil mixture (like the old-time blacksmiths
making horse-shoes).

Well, guess what?!  You've just popped the steel off the plate and lost
all your resonators again!  Consider this and you'll understand the
difference: a musical box comb is tuned to exact pitches with each
tooth separately tuned; if the pitch is changed in even one tooth, you
will have a dissonance that will be irritating if not unbearable.

Obviously the tempering needs to be done before you install the tooth.

In summary, the steps are as follows:

1.  Measure to extremely close tolerance the parameters of the tooth
to replace: length width, thickness, shape, damper anvil, weight base,
etc.

2.  Shape a piece of raw tool-steel to exactly that shape, plus a bit
left over on the end for the anchor.  Don't forget to drill the damper
hole in the anvil!

3.  File out and mate the tooth to the comb.  Note: This is the hardest
step of all the process!  Your tooth has to have a very tight fit in
the comb.  The shape you want is that the new tooth looks identical to
the existing teeth with the exception of the base.  At the base, you
should have a projection in the shape of a right angle triangle.  The
comb is notched to perfectly match the shape.  Also, the tip of the
tooth must be perfectly in line with the other tips in the comb -- no
room to play there when you consider that the cylinder is programmed
with musical tracks with a difference of around 1/2 mm between tracks!.

4.  Harden the tooth and temper it (also called bluing).  Heat the raw
steel to red-hot and without letting it cool down immediately douse it
in cool water/oil.  Clean off any residue from the tooth using wet/dry
sandpaper so that it once again appears to be shiny.  Slowly and gently
and evenly heat the tooth until it changes color first yellow, then
brown, then to blue.  Let the tooth cool down slowly to room
temperature and then polish it again with the wet/dry sand paper.

5.  Pre-tune the tooth to approximately the correct pitch.  If there
needs to be a resonator, attach it now, leave a little extra lead
attached so the note is too low -- it's easier to remove lead than to
add it.  If there is no resonator and it's a treble tooth, the tuning
is achieved by filing slightly at the flex point or the sides to of
the tip to lower or raise the pitch.

6.  Install the tooth to the comb.  Pre-heat the comb so it's barely
hot to the touch, apply flux so that the solder will stick, (both to
the comb and the new tooth), silver the mating surfaces (apply a coat
of solder) and put it in place.  Now heat with the soldering iron,
with enough solder to flow, and fill the void (which shouldn't be very
much!), make sure the solder melts evenly and that the tooth remains
in place, let it cool down naturally (or else you will have a cold
solder joint -- worthless!)

7.  Tune to the correct pitch and damper the comb.  Install comb in
box and you're done.

Now that I've told you this you will stop accusing musical box
restorers of being secretive, but I make this plea:  Do not attempt
this on an antique musical box comb until you have practised it several
times and you can make a perfect joint every time that it completely
invisible.  If you can't make an invisible joint, then please don't try
this -- you're dealing with an irreplaceable piece of musical history
that can be brought to the point of no-longer restorable.

Eliyahu Shahar
Kfar Neter, Israel