Zip is stuck or won't close
The cause is usually dirt, bent teeth, or a worn slider. First, pull the zip fully open and rub the teeth with a pencil (graphite acts as a lubricant) or a little petroleum jelly. Then move the slider slowly up and down. If individual teeth are bent, carefully straighten them with a pair of flat-nose pliers. If the slider no longer holds (the zip immediately comes undone again), gently squeeze the sides of the slider together with pliers – take care not to apply too much force or the slider may break.