I'm trying to find the correct window replacement sash for my window. Two of the cords for the lower sash have snapped, so it has been incredibly difficult to remove the upper casing to try to see the box. The pictures submitted show the only numbers (at least that I can see). It is clearer in real life, and the number on the right side looks like a 673, but you only have a 637 model. I was wondering if you could help confirm that these are the replacements I need, or if there is another way of telling what the number is. I'm guessing the windows are from the 1970's. Thank you for your help.
