Norcold doesn't sell new door seals for the Norcold 1200 and they say they are not replaceable.
Here's what I found when I took apart a freezer door to salvage the wood for a cabinet project.
There are no fasteners holding the door together. It's a sandwich construction with a front and back and wood facade held together by plastic moldings around the edges. The seals hook over the back (inside) of the door and go under the edge moldings. What holds it all together is the expandable foam insulation that must be injected after the door is assembled. To disassemble it, I just knocked all four edge moldings off. You have to break up the foam which makes it very difficult to put back together. Here are some pictures.
Here you can see the seal hooks over the inside of the door panel, and goes under the edge molding.
You pretty much have to destroy the doors to get them off or put new ones on. I'd think you'd have better luck cutting them off and finding similar profile replacement seal from another fridge, maybe a residential unit.