Double Hung Window Pivot Lock Shoe

Good Evening,

A couple of my double-hung window panes fall down when unlocked (top pane) or don't stay up/open (bottom pane) and it appears that the pivot lock shoe is missing on some and damaged on others. Attached is one of the window's label as well as the part needed. Your assistance in identifying the part I will need for replacement, from your website, or a comparable part would be greatly appreciated!

Thanks!
- Alex