Vinyl Traco Double Hung Window Hardware

I have a window that won't slide at all -- but it will tilt. I believe it's because one of my pivot lock shoes has sprung its spring: I can see a coil of hardware on top of it that seems to be aligned with the window frame in the working shoe. Attached are photos of a) the working shoe, b) its matching broken shoe, and c) some sort of hardware that screws into the window and seems to stop the shoe from rising. It's missing entirely on the broken side...