Metal Pin is Broken
Looks as if it is encased in the channel
Hello! Looks like the cam on your pivot shoe has broken. The cam is the round metal piece that takes the pivot bar and allows the sash to tilt in.
These can't be replaced by themselves, unfortunately, so you will need an all new pivot shoe entirely. Yours in particular looks like a match for our 15-177. I think this is what you want but you should review our dimensions to verify.
The 15-177 is compatible with quite a few different pivot bars. I'm very confident that we have a good match for your original, but I'll need a clear picture of it if at all possible. It would be especially helpful to see it removed and in undamaged condition, perhaps from the opposite side of the window. Figure that the more of it that's broken off or obscured, the less likely we'll be able to find a match for you.