Replace this fork valve?

Still rebuilding the forks on my '82 KZ750H. At the top of the internal pistons I found this black plastic valve.

It doesn't appear to badly worn, but is worn shiny on the external sides. Should these be replaced?

I think that's just some sort of spacer. Since it's not listed as a separate part, it might not be available. I just leave it be when doing forks - an old plastic part like that might be fragile & I'd rather not break it. The ones on the CSR are different & just look like a C-clip.