Window Pivot Shoe
correction: the 7/8 is the thickness
update 2: to be clearer, when I mentioned that the S140 was too small, I meant that the window did not fit into the pivot cam.
Hello, thank you for writing in. I believe you have our 15-192 pivot shoe, which works with the Series 170 and Series 171 coil springs. Take a look at the video below for more detail.
It's my pleasure. I'm afraid I don't have a measurement for the metal cam, but I am fairly confident that the 15-192 will work as a replacement for the pivot shoe you show in your picture.
Thank you for choosing SWISCO.com. We really appreciate your business and hope you will consider us for your future hardware replacement needs.