Buying Tips
The obvious route to take is via a specialist dealer. It will still be necessary to make judgements for oneself. Clearly, condition of the various elements of a musical box is vital.
Cylinder
Careful inspection will reveal any bent pins. The bass end or any sections that drive accessories (bells or drums etc.) are especially vulnerable. An excessive number of damaged pins will impair the music and repinning the whole cylinder is the solution!
The Comb
Look for excessive pitting to the surface of the comb, missing teeth and tips and badly repaired sections. Look underneath the Zither (the gantry suspended above the comb that supports a roll of tissue paper) if fitted, it may conceal damage. Corroded tuning weights (suspended beneath the comb) will be indicated by a fine white deposit around the affected area.
The Dampers
Should a whisper, click or grating noise be heard whilst playing, a worn comb or dampers that are out of alignment or missing will be the likely cause. Dampers are small pieces of fine wire fixed to the underside of a comb that curls up to meet the comb tip. In the case of a disc box, the damper, in the form of a delicate leaf spring, will emerge from between the tips of the comb.
Listen to and observe as many musical boxes as possible before making a commitment. Protect yourself with experience.