Crackling/Poor sound quality on iPod shuffle

Hello,

I bought an iPod shuffle (4th generation) about 4 years ago. About 2 years ago, I started to notice a problem where I often heard a crackling, fuzzy sound while I was listening to music. It sounded like an out-of-tune radio. Sometimes that was all I heard, and sometimes the music was barely audible over this noise. After some fiddling around with the iPod and earphones, I was usually able to get it to work again. But often, all it would take was for me to bend down to tie my shoes, for example, for the wires to get jostled up and for the noise to come back. Sometimes the iPod was completely or practically silent, or you could hear a low hum of crackling. Then, the problem went away for about a year, and only recently came back. I like to use the Shuffle for running because it's so small and I can just clip it to my shirt, but I am very annoyed with this issue. Is there anything I can do to try to fix this problem, or do I simply have a defective device in which case nothing can be done?

Thank you very much for your help.