When replacing a broken string which is understrung, most of us use the extendible antenna method to get under the bass strings and reach the hitch-pin. I have found that this procedure can be made even easier by adding a 1/2 inch plastic or wooden bead (from a hobby/craft store) to the tip of the antenna. Drill a hole through the center of the bead to accommodate the antenna tip, CA glue in place, file half of the bead away, and then use the hemispherical side as a "sled" to slide over the understrung strings. This prevents the hitch end of the new string from getting caught or sliding under any of the existing strings. A drilled-out file handle or large diameter dowel mounted on the back end of the antenna makes manipulation still more comfortable and easy.