Not long ago there was a discussion of print hammers which wound up that they were a form of grommet. I wonder if anyone has checked out J.J.Short for the parts. They make all sorts of specialized rubber parts including typewriter platens See: <https://www.jjshort.com/Rubber-Grommets.php> -- Richard Knoppow 1oldlens1 at ix.netcom.com WB6KBL