Hi all I have a measuregraph (it was used to measure fabric in the deptment stores) and we are trying to restore it. Does anyone know how to get the cover off to get to the inside? Do you need a key? Does it just lift off? It is dated 1922. Any information would be of help. I am hoping someone out there worked in a fabric deptment and used one of these. I remember these machines when I was a little girl and that is how fabric was measured.