Megane steering rack issues

Hi guys I have noticed a knocking noise from under my 03 megane when I go over uneven ground. Think I've found the problem. I looked at my ball joints ect and found nothing, but when I got someone to turn the wheel vigorously I felt it knocking from inside the steering rack. So I took off the boot and the noise is coming from just inside. Now is it a case of gettin a whole new rack or is there a way to fix it? Also how hard is it to do? Thanks everyone :d