Screen spline

I'm afraid I don't know what kind of spline you need. Cole Sewell has also been out of business for a long time, so there is the unfortunate possibility that your spline isn't even made anymore.

Before I say anything for certain, I think it's best if we get photos. Please remove a small, undamaged sample of the original and show me a clear picture of the end profile. The video below will explain what I mean.