I have had some luck, with shortening tights on my regular sewing machine, rather than the overlocker. I put some sew-in interfacing under and on top of the tights, stretch them slightly, and then sew across the leg with a tight zig zag or lightning stitch (stretch stitch). I will go over the seam a couple of time to be sure, and then trim back the excess tights, and interfacing. The seam is still a bit bulky, but not as much as the overlocker.