A friend needed the top part for his Phantom retractable screen. With the broken part in hand, a set of calipers and a picture of one that was not broken, I went to Fusion 360 and created a replacement.
The broken one had the letter R embossed inside so I assumed it meant "right"....it's on the right side when viewing from inside the home.
I mirrored one for the left side and uploaded that .stl as well.
*Note: The holes were purposely not countersunk as far as the original because it left very little material (1 wall) on the edge and did not print well. You can see on the original one in the pic that it was also weak there and cracked on the corner. The screws just won't sit as flush as the original.