As I have mentioned, there seems to be two kinds of 'bar' the thread goes around after it goes between the disks. One is mounted on the plate and the other kind is attached to the tension post. They take different springs. One of the MW machines had a bent tension spring - looking at it some more. Someone had lengthened that spring for some reason. It was wearing on the tension plate. The kind with the post on the plate is a little bit easier to rebuild because it has less parts. The 3 I have came with the plate, a tension post with a pin in it, a can they seat in with two screws holding it. Then all these tensions had for parts were 2 disks, a washer or a cup that fits over the tension post with a bar for the pin to hit, a beehive spring and a nut. That's it. Very simple and similar to the old Singers.