Repair NAD headphone jack?

[simonboyce]

Hi: I recently bought a used NAD 7220PE receiver. It mostly seems to work fine (still checking it out), but the headphone jack is completely messed up. It adds massive distortion. I have little/no experience with electronics, but I'm wondering how DIY fixable this might be? I also have a friend who knows about electronics who could help me - eg. so I don't electrocute myself on a capacitor!

Thanks, Simon