Evan and Yanyan noted that PCALX was malfunctioning since Wednesday (LHO alog 43959 and 55257). Jeff has added an alert that will notify operators if this happens in the future (LHO alog 55257). 

Since, simply switching on and off the OFS control loop, didnot bring PCAL back, I looked at the PD singals and saw all PD signals were reading zero values. I tried switching on and off the laser remotely but still no signals on any of the photodiodes. Further investigations (on AOM status and/or the laser itself) will require  going down to the endstation. Stay tuned!