Some machines, especially vintage straight stitchers, don't allow for moving the needle over one notch. The machine I made my first quilt with was like this. I had to use a pack of post it notes to keep me consistent. I agree with PaperPrincess and others who have posted to make test pieces til the part that is important measures as it should, not the part that is to the right of the needle. the tutorial linked to is very clear to me.