One store here charges $40 and another $75. They charge $85 for a computer machine. They said they clean the sticky stuff off the disks, and I assume they mean the tension disks. The machine gets so it won't allow me to adjust the tension and starts pulling the bobbin thread when it needs a cleaning. I like the $75 store the best, but both my machines are computerized and that means $85. That seems to be a racket to me. Until I learn to properly clean it, I'm stuck. Nothing beats a clean machine though.