Once you have removed the bottom cover you should have clear access to the music player.

Locate the music player and check to see if it is visibly dirty or clogged.

If there is any amount of dust or dirt on the music player it should be cleaned.

Using the straw that comes with your air duster, aim the duster in a way that the air will push the dust away from the music player.

If cleaning the music player is not enough, you may need to refer to the Music Player Replacement Guide