Gasket

Thanks for reaching out to us. It's hard to make out what your gasket is based on these photos. When it comes to this kind of seal, we like to see the end profile. That allows us to analyze the shape and pick out something that installs in the same way and fills the same gap. I'll share a video below that will explain exactly what we need to see.

Can you also verify that this is an Andersen brand patio door? Based on what I can see in your photos, this doesn't look like any series door made by them. Check the corners of the patio door glass to see if there is an etching stating the brand and code number of the doors. Andersen usually puts their branding on the glass, while other companies don't.