After the 10:16 UTC lockloss, DIAG_MAIN began reporting that, in addition to the known PCAL Y issues, PCAL X was also off by more than 1%. Trending the RX PD OUTPUT shows that the output changed in a step coincident with the lockloss. I'll not attempt to do anything about this at the moment and let those in the land of the living decide what actions to take.
The Y-end TX PD doesn't show any changes during this time and hence that end would not have been cause of any problem. The X-end changes are small and hence wouldn't have been a cause either. Actually the full rate X-end channel (16 kHz DQ) doesn't show any changes (first plot) and so the changes we see in '*OUTPUT' channel might be some artifact. The small changes we see in Y-end is response to the lock loss. The second zoomed-in plot show that the changes in Y-end happen after the lock loss and only in RX PD. This is indication of test mass moving (oscillating) after the lock loss, due to kick. The PCal could cause lock losses when most of it's power (~100%) changes suddenly or the optical follower servo loop becomes unstable. It wasn't the case here.
