Good day, I have this really frustrating problem. I am trying to make a t-shirt, I have a domestic straight stitch sewing machine, and industrial serger, coverseam and twin needle straight stitch machines. Now, when I get to the neck band of the t-shirt, I can serge the neck band to the neck line, but I struggle with the topstiching to finish it off. It’s a cylinder arm coverseam machine, and when I sew, I try to keep line, where the neck band and neckline meet, on the right side of the t-shirt, I try and keep this line centred between the two needles doing the topstitch, but it never stays straight, it always ends up going a bit skew, and even if I try and bring it straight again, by the time I’m done it looks really unprofessional. My question is, is there a certain technique to keeping the stitch straight which I am missing here?