here is a good discussion of the clutch part of a machine:
http://vssmb.blogspot.com/search/lab...clamp%20washer
They can get very stuck - you may have to work at it a bit to get it unstuck. I think that discussion is somewhere on this thread but I have no idea where:
http://www.quiltingboard.com/vintage...y-t236275.html it is a good read though.