plastic clip at top of window channel is broken

I have Lawson SH 7500 Windows (about 15 years old) THe plastic clip at the top of the window channel is broken. (So it doesn't push the channel balance down into place when reinserting the window. Picture 5601 has the good clip on the other side in place. Picture 5600 has the broken clip misssing. The other three pictures show various views of the two clips - one good, one broken.