Floor vent rebuild

Has anyone ever rebuilt or otherwise repaired the floor vents on their S30, the ones operated by the pull knobs under the dashboard?

I'm starting to reattach all my interior bits and pieces, I noted that after only 54 years, the "rubber" that seals the vents closed has cracked and broken off in a few places which is plainly evident in the photo. That will make for some drafty driving in cool weather.

I estimate the material thickness at about 1 mm (1/25" or 0.040"). I see 0.040", 60A durometer, adhesive-backed, transparent silicone rubber sheeting (about 1/2 square foot) on Amazon for $11 so that's my target material at the moment as the silicone should never "dry out" and get brittle. Anyone have an alternative?

Also, the movable flap looks to be held in place by and pivots on two pins that protrude into the air horn and look to be retained by plastic, friction-fit washers. Has anyone disassembled one of these and determined if everything survives the process to then get reassembled?

Edited 1 hour ago1 hr by Seppi72
correcting typo