Operator for Casement Windows
Thanks for posting! The issue you are describing typically occurs when the operator is stripped. When this happens the entire mechanism needs to be replaced. However, there is also a chance it could be the hinge. I would suggest detaching the operator from the window and closing the window manually. If it still works fine you'll need to replace the operator.
To replace the one you have, you'll need the 39-031 EntryGard Dual Arm Operator. The opposite version is the 39-032. Be sure to look over the compatible hardware and accessories below to determine if you'll need any of them for the repair.
If you find you need to replace the hinges, start with reviewing and comparing the 36-048 2-Bar Hinge Set. The set can be used to replace the top and bottom hinges, for right and left handed applications. It is strongly recommended to replace both the top and bottom hinge at once, to ensure they'll be a fit.