I have the magnetic seam guide but don't use very much. Mine would shift a little on me while I was sewing. I don't know if I was doing something wrong or not. I'm also trying to find a way of marking a scant 1/4" on my machine, too. I'm using a Kenmore and I can't move the needle over and with marking the scant, I'm starting to get into the feed dogs. Any suggestions?