Every year you should take your sewing machine in for service.
Sew & Vac offers a wonderful deal new sewing machines. They include 5 years of free maintenance. They also offer classes and help with your sewing projects. Everyone there is so nice and helpful.
I had them service three machines: Babylock Evolution (overlock), Pfaff Expression 2.0 (my everyday machine), and my Empress long arm quilter (Tin Lizzie). Only one of these was bought in their shop but they service all machines and that service is great. I was having terrible problems with the long arm quilter. I'm so glad I took it in. It needed a timing adjustment, which was the likely cause of all my troubles.
Happiness is a truck-load of serviced machines.