There is no crack in your string retainer (the plastic component above the neck that holds your strings in place when you remove your neck). Our string retainer is made from two parts that come together like two jigsaw puzzle pieces. We designed the retainer in two components so that a luthier or guitar technician can remove this piece and have access to file down the nut without removing the strings. Click the image below to order a replacement. NOTE: We have Two sizes one NARROW 1 11/16″ and one STANDARD 1 3/4″. If your Guitar ends in the letter “N” you need the narrow version, otherwise you can order from clicking the image below.