Hey Daniel,
Is there any chance you can pry those old corners out? We would really like to see what it looks like when it's removed from the frame, not to mention it would be easier for you to get a few measurements.
If you can remove it, take a couple pictures and send them to us so we can get a better idea of what you'd be able to use as a replacement.
I tried once with no success. The remaining corner pieces are stuck within the frame. I will try again and report back.
Dave, I wanted to thank you for taking the time to find that video explaining how to remove pinned corner assemblies. I'm pretty sure my screen door doesn't have those. Anyways, I went to the "orange" store this morning and with the previous homeowner telephone number the staff was able to find the order as they were installed by them in 2006. It turned out that they have the screen door in stock for $44. I went ahead and bought as it wasn't that expensive and saved me time.
Thanks again for your help.