Somehow c1sus was in a very strange state. It was running models, but EPICS was slow to respond. We could not log into it via ssh, and we could not bring up test points. Since we didn't know what else to do we just gave it a hard reset.
Once it came it, none of the models were running. I think this is a separate problem with the model startup scripts that I need to debug. I logged on to c1sus and ran:
rtcds restart all
(which handles proper order of restarts) and everything came up fine.
Have no idea what happened there to make c1sus freeze like that. Will keep an eye out.