73 & up Dusters/Dart Sport inner "Cat Wisker" removal question

I have a 73 Duster & want to replace all of the window sweepers/cat whiskers, inner & outer. How are they attached to the plastic upper door pieces? I see the metal channels they are attached to, but not sure if they are removed with the sweepers OR the sweepers are removed FROM them. I don't see any fasteners. The metal channels, which look like they are snapped in place on the plastic upper door trim pieces, may have to be reused, I'm not sure & I don't want to ruin them by removing them the wrong way. Anyone have experience with these?