Try to sift through threads here (imaginative search at the top of this page) and maybe you can find answers where and how to do it, if you are not too good with manual work required. I remember coming across posts with people mentioning who did their work in similar situation.
I believe, not having any proof for it, that the benefit may be in improving contacts after so many years. As far as the actual wire goes, unless it is physically damaged, if it ain't broke, why fix it? It took you this far and some damage may be done while hoping it will make it even better.