I have a Mac style waterproof coat that I have had for years. It was originally taken in by a tailor when I first bought it but time has taken its toll and I now need to let it out. I notice that inside the coat I can see the old stitch marks from the original stitching (folded over so they are viewable from the outside). Does anyone know if it is possible to "repair" these stich marks? Obviously I am keen to retain the coats waterproof features but I am also keen to keep to nice aesthetic.

Thanks in advance.