Years ago a repair man told me a sharp needle is the secret to a long life of a sewing machine. He's words proved correct - I've had my machine for 58 years - I use it almost every day. I change my needle and clean bobbin area first - before I begin to sew. On my embroidery machine, I change the needle every 3-4 hours of dense stitches even if the pattern isn't finished. Needles are super cheap compared to repair bills.