There is a much easier way to install an invisible zipper. You do need to hand base and the result are much more consistent. The problem I have always had with the installation demonstrated is that there is frequently a bump where you sew up the seam to the zipper. This method eliminates this. Also I have found that if you use a strip of iron on interfacing about 1 1/2 inch wide on both sides of the opening( place on edge of fabric before starting) the fabric rolls much better where the two side meet. In this method, which I found in my Janome 11000 manual, sew the seam up first, using a regular seam allowance up to the opening for the zipper. Then you machine base the opening , using a 3/4 inch seam. next you open the zipper and using the invisible zipper foot you sew one side of the zipper in place. The zipper teeth are up against the seam. Then you close the zipper and sew the tape on the other side to the seam allowance on the opposite side. Then on the side you sewed first you sew the tape to the seam allowance. At this point you open up the based seam, move the zipper tab below the opening and then sew the second seam close to the teeth. Last pull the zipper tab back up and you are finished.The only difficult pat of this method is moving the zipper tab below the stitching before the final sewing of the second side. If the stitching is not close enough to the teeth you can resew it with out tearing anything out. If you cann't follow my directions go the the Janome site and look up invisible zipper application.