Need Correct Arm for Truth 31704

Is there any other identical awning window in the house? If so, does it work correctly, and can you confirm if it's the 39-239B? If so, then I'm not sure if an incorrect operator is the issue--at any rate I am not sure if it would connect to the window properly at all without some heavy modification if it was not. Remove the operator and try manually opening and closing the window. Does it seem to struggle to move? If so, you might need new window hinges. See if either our 36-048 or 36-049 match what you need. 

Maybe I can help! From what I can see in your photos, it looks like the 39-536 pivot shoe is hitting the bottom of the window sill. My guess is that it's possible the 39-556 track was installed too low, causing the operator arm to hit. Take a close look at the window to see if you can indeed move up the location of the track with out damaging the window frame or glass. If that doesn't seem possible, your other option would be to see if you can move the side hinges up a little, to give the window a little more play at the bottom.