It's a little, maybe 1/4" x 1/4" square hole punched into the window frame side, that is supposed to have a clip with a round hole in the middle, that the screw that holds the top of the balance, goes into.
I dont know how to better describe it. And really dont see how a picture could help. One side of the window still has the clip, the other side, the clip broke in half and fell down into the void.
