Zipper tip for jeans -- if you have a tooth break, just cut off the teeth off both sides of the old zipper leaving everything else in place. Then you just line up your new zipper along the existing sides of the old one and zig zag in place with a good thread color. You do lose maybe half an inch at the bottom, or you can cut in a slit where you can slip in an extra inch or so, put a handle on the zipper head if you do that!