Often when your sewing machine doesn't seem to be sewing right it may just be that your needles need changing or they are the incorrect needle type for the fabric or thickness you are trying to sew.
Some of the most common signs that your needle needs changing is when:
- It skips stitches
- The tip is no longer sharp (the point is blunt) so the fabric is difficult to sew
- The needle is bent
Synthetic fabrics, pvc's and heavy fabrics will blunt the needle more quickly so they need changing more often. A blunt needle or one that has a burr (a rough spot) can cause the thread to break or snag fabric.