I'm going to mention something that all musical box fans know but that
player-piano people (like me) learn only reluctantly.  When visiting
your friends who have musical boxes, DO NOT TOUCH the boxes without
express and separate permission for each box.  Some musical boxes can
be damaged by incorrectly moving the control levers.  Equipment junkies
(I'm one) like to think they can understand the basic aspects of any
complicated device by fiddling with it for a while.  This method can
result in grave damage to the comb, pins, spring, or other parts that I
haven't even heard of.

My advice?  Think of each box as being at 15 kilovolts, and keep your
hands in your pockets at all times!  Your friends will appreciate your
respect.

--Peter Neilson