Problem: the jewelry music box does not stop playing when the lid is closed
Cause: the stopper does not stop the rubber propeller when the lid is closed, therefore the propeller keeps spinning and the music box playing.
Solution: grab the stopper end with pliers and turn it a few degrees counter-clock-wise:
Use a rag between pliers and stopper to prevent scratches.
If that does not help, you might need to remove the glass to get access to the stopper pin. Then you will be able to bend the pin to the correct position.
If the music box contains a glass cover you can remove it with a suction cup.
Make sure you hold the glass with other hand to prevent accidentally scratching the music box.