Hello there. To clarify, the casement window refers to the entire window sash, frame, and components. See the video on this page that explains the 'anatomy' of a casement window. Now, at the very least it sounds like you might need to replace the window operator as well as the track it connects to on the sash. See if the 39-028E matches what you have. Let me know if anything differs in the measurements. For an accompanying track, see the 39-533. For a new handle, see the 39-114L.
Now, if you remove the old operator and try manually moving the sash in and out, and it cannot do this properly, you probably need to replace the hinges on the tip and bottom of the window as well. See if the 10" 36-048 set matches what you need. Let me know if you have further questions.
