And you'll never guess what the problem was -- I hadn't tightened that screw at the back enough! You see, when I tighten the screw it clicks as it turns round. I thought that meant it was getting too tight, but it doesn't; it's just the sound it makes. The screw's being too loose meant that the front part of the foot moved forward and covered the needle hole on the sole plate. Now the screw is nice and secure the foot stays where it is supposed to! I'm so pleased!
Anyway, the adjustable zip foot is considerably smaller than the standard presser foot (see photo at left).
I wondered why the foot seemed to work once and then never again. The packet says it fits most low shank machines, and I'm so glad it turns out that it does fit both of mine!
Note: when I sew with this foot, the stitch length is for some reason automatically shortened, and when I try to backstitch at the end of a line of stitching, it won't feed backwards properly. It works better if you stablize your fabric. I tried it using the instructions of a pattern I don't want. It works even better if you put paper on top of the fabric, as well as underneath.
I wonder if these problems would occur with a machine-branded adjustable zipper foot. Do you have one? How has it worked out for you? Please leave your comments below. Thank you.