During my time online on other forums I've seen numerous posts about replacing their virus knobs, but it seems like there wasn't an easy solution to source them.
I've found one solution for anyone looking to replace or change theirs (can confirm I've bought and used these knobs on other gear, and tried them on the virus also...fits perfectly)
Make sure to get the super knob (not the 90 degree super knob or you'll be stuck with a knob that doesn't translate)
Check the super knob here, just type "virus" in the search box...
https://store.djtechtools.com/…oma-caps-knobs-and-faders
cheers!