It's entirely possible, even on a new machine, that the leaders aren't even or straight. This will *especially* happen if the frame is out of level. Check the manual for how to make sure it's all straight and level. The other thing to make sure of is that you haven't tightened the rollers down too tight - this can make them bow and can make all kinds of things wonkified. They're supposed to be able to spin fairly freely when they're loose. Stand at one end and look down the length - you'll be able to see if there's a bow in them somewhere. Finally, follow Dawn Cavanaugh's instructions on tugging on the canvas leaders to make them wear evenly - and if ALL else fails and your leaders still aren't even, you can use your horizontal channel lock (it's so nice to have a millie
and sew a straight line along the edge of your leader in order to give you a nice even mark to pin them to.