Depending, on well worn rigs, I have had them function on a single remaining ring. On new rigs that are still breaking in, you may not be so lucky (read wait until you get a new ring so you have a full set in place, and don't possibly destroy the other rings).
But will pose this, what caused the ring to break in the first place. If by you installing, removing the rings, then better learn the correct way to remove them (fingernail to lift up just the end of it out of the slot, then ride the ring around with your fingernail to slip it gently out of the slot).
If the ring broke during live fire, then check the key bolt to confirm that it's not protruding into the gas chamber space, the threaded section for the bolt down not have bottom burs that may be protruding into the gas chamber space, and the step cut for the gas section is not milled so far back that the front gas ring escapes it confined space that it expands outward and catches such edge as the bolt goes to lock back up while the ring is trying to be decompressed.