I'm missing the black piece that's circled in red. The piece slides along the track that's attached to the bottom of the sash. The post that's at the end of the crank mechanism seats into this black piece. This is a Simonton casement window.
Casey from SWISCO responded:
December 10, 2021
Hello,
Take a look and compare the 39-529 track slider to an undamaged part removed from the track. Thanks for posting!