Stuck casement lock
Hey there!
Thank you for reaching out to us. I'm afraid this type of lock doesn't adjust. It sounds like it needs to be replaced by what you describe. Start by taking a look at the 38-096 and 38-139. Review the specifications below and see how they compare with your old lock. Note that the projection of the fork is especially important.
It sounds like your sash keeper might need to be adjusted instead. I recommend you check the keeper on the sash to see if it can be adjusted or needs to be repositioned on the window.
I'm afraid there isn't a video we can show you but I believe the keeper is shown in one of the photos you've uploaded. I circled it below. You may also want to check it for any signs of wear or damage.
