Trunk door issues

Hi,.....on my Champion trike the bottom trunk door was floppy. So I took it apart....it appears there is an L bracket that looks like it was pressed on to two posts.....after cleaning up the rust and painting the parts I tried to press them back on with a hammer and punch. They stayed on all of 15 minutes after I got it all back together. Is there another way to keep these brackets on or another way of fixing the door. Hate floppy doors lol lol........thought of fiber glassing them in but really don't want it permanent....thanks....