How do I get these blocks to release 15-233 would be the replacement.

Hey there! Thanks for your patience during this busy season. You would need to use a Flat blade screwdriver to press down on the metal blade inside the shoe. Take the screwdriver and press down on the back end of the blade away from the knife hooks. Be careful! The balance is under pressure and could shoot up in the track of the window, so take great care.