I would try Sewer's Aid (I lubricate the spool with a few lines and touch it to distribute the silicone, then touch the needle eye as well) sometimes I reapply a few times in each project. Also try slowing down, using a new needle (try a larger size), clean the upper thread track with a dollar bill or unwaxed dental floss. A tiny bit of thread or a small burr can cause the thread to shred. Also check bobbin area, clean well, sometimes it takes a piece of fluff. I would also lengthen my stitch (try all on a test sandwich) and see if that helps. Good luck.