We first removed the patch and all compromised yarns from the pile. The rug looked like it had a neat square cut from its edge.
Next, we rebuilt the missing warp and integrated it into the pile of the rug. The white vertical strands are the new warp. They are seen in the above photo from the back of the rug.
In the next step of this Oriental rug restoration project, we reconstructed the weft creating the grid-like structure on which we knotted the pile. The blue yarns in the bottom of the photo are the newly knotted pile yarns. --www.traditionalrugrepair.com