I am new to machine stitching. I recently bought a 50 yr old Singer 99K which goes through my tooling leather fine. However, when I look at the stitch underneath it is nice and straight but the stitch on top appears to zig zag. The best way to describe it is that the thread appears to go from 6 o'clock to 12 o'clock in the holes rather than 3 o'clock to 9 o'clock (I hope this is making some sense).
I am using bonded nylon with medium commercial Singer leather needles.
Can anyone advise what maybe happening here?
Thanks
Matt
