How to Fix Every Common Zipper ProblemCheck out this post from Lifehacker:http://lifehacker.com/5975700/how-to-fix-every-common-zipper-problem
I have always had to cut off a zipper to fit my project, then I throw the other end away.  My daughter  just reminded me that "hey", I should replace the other part of the zipper with a new slider, and save some waist.  Dahhh... sometimes we need our children to supply us with knowledgable answers!You can buy the zipper sliders in any fabric store, craft store, walmart, or of course on line by googling "slider for zipper".  They make wonderful "zipper rescue kits", "fix a zipper - pull resplacements", and much more.