Found an option for replacing the rubber feet on my 1952 SC Skyriter. Used a Hillman Group grommet, #55050-E, with a groove diameter of 1/2", and a groove thickness of 1/16".
via u/TomMahalla at https://www.reddit.com/r/typewriters/comments/1vkvwkx/smithcorona_skyriter_replacement_feet/
He also suggests: Jandorff #61506 Rubber Grommets 3/4" OD x 7/16" ID x 1/4" thick x 9/16" groove diameter x 1/16" groove width which are sold by various places including Ace Hardware
