I noticed yesterday evening that I wasn't able to engage the single arm locking servos - turned out that they weren't getting triggered, which in turn pointed me to the fact that the arm transmssion channels seemed dead. Poking around a little, I found that there was a red light on the CDS overview screen for c1rfm.

• The error seems to be in the receiving model only, i.e. c1rfm, all the sending models (e.g. c1scx) don't report any errors, at least on the CDS overview screen.
• Judging by dataviewer trending of the c1rfm status word, seems like this happened on Sunday morning, around 11am.
• I tried restarting both sender and receiver models, but error persists.
• I got no useful information from the dmesg logs of either c1sus (which runs c1rfm), or c1iscex (which runs c1scx).
• There are no physical red lights in the expansion chassis that I could see - in the past, when we have had some timing errors, this would be a signature.

Not sure how to debug further...

* Fix seems to be to restart the sender RFM models (c1scx, c1scy, c1asx, c1asy).