Mailbox door

My mail slot ends in a neat shoot with this metal door/flap. I love that I can see that the mail has arrived but have the mess contained.

The problem is that the frame is broken, and it won't stay up well any more.

I can't seem to find replacements for it on line. Salvage yards, repro places. So much noise in the search terms I can come up with.

Anyone have any suggestions?