window shash brake/locking mech. that tension spring goes into

Thanks for posting. This is called a pivot shoe. I am confident we can replace yours, but I'd like to see an undamaged version, just to confirm the style of the cam your shoe had. We will also need to know the width and thickness of the pivot shoe--these are the pertinent dimensions for identifying a replacement. In the time being you can view our selection of pivot shoes here.