Whirlpool ET20DKXSN01 freezer door gasket repair

I have this freezer refrigerator in the garage and it runs fine but I'm having problems with the gasket on the freezer door no longer sealing. The rubber gasket itself is still fine, though maybe in need of a scrubbing. The gasket is held to the door by plastic strips that the gasket hooks onto, and this strip is attached by 1/4" hex head sheet metal screws spaced at 4" intervals. The plastic has become very brittle and has disintegrated on the bottom and left side.

It looks like it was designed to be replaceable but trying to find any suitable parts for fixing this are elusive. I'm not sure what the correct term for what I'm looking for is, and searches for clip or bracket or bezel turn up nothing. I contacted Whirlpool directly to see if I could find something, but they couldn't give me any information this old model. No luck talking to local appliance shops either. Any leads?

For reference, here's a shot of a larger piece I just broke off while trying to detach it from the door (about 4" long and 3/4" wide):

https://imgur.com/a/jJ64QpX