Too Long Zip?

What do you do? The solution is to sew a few stitches over the zip teeth before you cut your zip to the length you want. Make sure your  zig-zag stitch tension is tight (like a button hole stitch).

I've never had any problems with my shortened zips, they laste as long as one bought to size.

Set the sewing machine to zig-zag

Tighten the tension and zig-zag over the zipper  teeth in
the same spot

This is how the end of the zipper should look

Just to be sure I re-did my stitching switching
 to my trusty Bernina. Next you cut the zip about
an 1" away from the stitching using
 pinking scissors.