Well because of my inexperience, when I hammered the long pin out I was destroying the fiberglass on top of the box and didn't know it until I had it apart. What a disappointment. What I should have done is put something wooden or metal on the door edge so the door was not cutting through the fiberglass box.
This slowed me down. I recovered from this by gathering the pieces and supergluing. There were 2 fairly large chunks. Then to fill in the parts that turned to dust I used superglue and baking soda to make my own super strong plastic. After it cured I smoothed it with a dremel-like grinder. It came out decent. I think it's good to go for another 50 years. When I put the door back on, I padded the door edge with a popsicle stick and therefore did not damage the fiberglass on the bottom of the box.
The original rubber was interesting. I think when they made the door, they submersed it into a mold with liquid rubber and let it cure to solid rubber. I cut it off while trying not to destroy it so I could use it as a template.