Why can't I hear the music on both side of my earphones?

Why can't I hear the music on both side of my earphones?
I had this pair of earphone since Christmas and has been working fine, but all of a sudden I cant hear the music, I checked everything on the device the Bluetooth still connects to my phone and charges well, but I have to move the wires around and you can hear a faint sound but has to be in a certain position, I was told to open up the earpiece but I have no way too open, need help!!!!!

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