I have a Bernina 1530 and the other day while my DD was using it, she asked what the screw was for on the back of the presser foot. I have a multi purpose presser foot (can't remember the number of it) and a piecing presser foot (number 37) and they both have a little screw on the back but I don't know what it is for. I checked the manual, but couldn't find any mention of this or what it is for. Can anyone tell me what the screw is for?
Found this link with pictures of no. 37 and no. 20. You can see the screw.