I've tried to read what l can on these old machines and enjoy learning all I can about them. I did read in the book, AFTER I printed a new one that " Under no circumstances must the screw EE be loosened." OOPS, I did and took the latch off so I could clean out under the bobbin case. I did sew with it after, and it did OK, so maybe I didn't do anything so bad. I'm hoping!