That is my most favorite machine to work on! I notice that the buttonhole mechanism is engaged. So when you go to sew, it will act like it's possessed, and do something you don't expect. It's just the buttonhole system -- the middle knob that's second from the top, on the right. Turn it clockwise until the indicator line is pointing straight up. The plastic motor covers become brittle, and I see a lot of them where the plastic has rotted so bad, there's nothing left for the screws to screw the inner cover into. These machines hold their loop lift and return motion timing settings better than any machine I've worked on. But... the needle/hook distance and thread passage need adjusted quite often. The camstack gear and vertical shaft gear can become cracked if they're the older style. But they can be replaced. The decorative stitch selector lever can freeze-up. But it's nothing that a little "special sauce" won't take care of. Enjoy your machine -- it's a great one!