head phone jack sound distortion

Hello,

I have an IPhone 5 that I got from someone to fix and keep. Currently everything on the phone works except for when I plug in headphones the music when someone is singing is very distorted. I have restored the phone, cleaned the headphone jack, and tried different headphones. The other weird thing is if I pull the headphone out a bit it sounds perfect. Then I push it in and it is distorted sounds like someone is underwater.

Background I had to replace the screen it was cracked the rear camera had black and purples spots so I replaced that and the home button was not working. I also chose to replace the back and middle housing as it was very badly abused.

I only finished working on it last night didn't have the gusto to open it up and check the connector. Any help is greatly appreciated, thanks.

Ben