Sound Still Distorted with Replaced Headphone Jack

A few days ago, my headphone suddenly played distorted sound when plugged in my iPhone 5S. I tried them on a different device and everything worked fine. So I went to Apple but they only offered the usual expensive replacement of the entire device. So I bought the "Lighting Connector and Headphone Jack" part and replaced mine with the new one. I was quite happy to find that the iPhone still worked after the reassembly - apart from the headphone jack!

Any idea on what might have gone wrong?