I restarted the PSL this morning after what was apparently a shutdown initiated by the front end watchdog.

The Beckhoff status screen showed "Power error (WD)" in red and the trends show the NPROOK and WATCHDOG channels triggering at the same time (16 Hz resolution).

The second plot attached below shows the front end output power over the past 100 days.  The steady decrease in power is at a rate of about 6-7 percent per 100 days.

I recall that the threshold for the watchdog to trip is a 10% change in power from the time the watchdog was set.  It this is correct, then it doesn't appear that the watchdog should have tripped due to the slow decrease in the output power.

I will investigate further with the PSL team.