If you know the size im sure a regular O-ring from an automotive store would work, you might even find one online like McMaster Carr. If you have one good one left, gently pry it off with a blunt tool or and o-ring pick and see what you can get locally, I will check with Shaun Evans, aka Yellowaircraft and see what he says, He may be able to get one for you. Ill check in on this for you. Shoot me an email in a few days, John [email protected]