Having seen the pictures of the damaged music box, I would have to say
that to replace the whole case because of that minor damage would be
downright silly.  This minor damage can easily be repaired by a _good_
refinisher without you being able to find the damage afterward.  Find a
finish technician who can repair it and touch up the finish who can do
French polish.  If they can't do French polish or don't know what it
is then they are not competent to work on an expensive music box.  He
should not need to refinish the whole box unless you want him to do so.

I would definitely investigate the insurance company because repair
will be several hundred dollars especially if you have him touch up the
whole thing and French polish it all out.  My shop has a refinisher who
can do it but he is way overworked so I will not offer.  You should be
able to find one in your area.  If you have an auction house or antique
shop that sells hyper expensive antiques, ask them who they use.  If he
has restored a $30,000.  chair then he is probably qualified to do your
music box.

D.L. Bullock
St. Louis
http://www.thepianoworld.com/