Garden window

Thank you for your patience in this matter. I think you could have either the 38-138 or 38-139 Roto lock on your window. You say you can pull the lever down halfway, but usually pulling the lever down locks the window. The operator might not be the problem. It could be that the locking tie bar inside the window is not lined up correctly. I suggest having someone on the outside pushing the window closed tight. When it's pushed tightly closed on the outside of the frame, try to unlock the window. If that fails to do the trick you might need to cut off the lock off the window to get to the locking mechanism. That isn't the easiest thing to do, so you may want the help of a local handy person.