Identify the problem. The cause for repair might be obvious, such as a broken pane, or it might be concealed by the window's mechanism. If the problem seems mechanical, open and close the window slowly while looking and listening for clues. Check all sets of hinges separately and inspect the screws and the braces to find the problem.
Remove the window so you can better identify the problem and repair it. Remove the sash first by taking the screen off the window and then disengaging the operator arms. Make sure window is unlocked. This will give you access to previously hidden parts of the window.
Order parts for the awning window from the window's manufacturer or from window parts supplier. Identify whether you need minor parts, such as stretcher slips or larger, or more integral parts like a sash, operator crank or crank lever.
Install and test. Follow the part and window guidebooks to install the new part. Make sure it works by testing the window multiple times. If the window is still problematic, make sure there are no obstructions from the repair in the window's mechanism. Also, give the parts a quick cleaning with a damp cloth so dirt doesn't get in the way.