After a bit more searching, I think I found the answer to my own question. The name of the part is a bumper grommet. A site called morbidstix.com has them at $5 a pair. Bumper Grommets
This guide could be enhanced by showing the L1/L2, R1/R2 button cluster in some photos. I needed to replace the silicone grommet underneath the buttons due to Sony's design flaw of having R2/L2 press on the silicone with a blade shaped extension.
This guide could be enhanced by showing the L1/L2, R1/R2 button cluster in some photos. I needed to replace the silicone grommet underneath the buttons due to Sony's design flaw of having R2/L2 press on the silicone with a blade shaped extension.