At present, the IFO cannot reach PRMI 3F locked. During Find IR resonance, ~ a 5Hz peak can be seen in the DARM sensitivity. (Photo.1)

In addition, the earthquake frequency range seismic noise is now increasing, as shown in photo 2. This phenomenon happened when the volcano in Hawaii became active in the past.

Before PRM was aligned, the ETMX GR resonance was lost suddenly during Find IR Resonance.

Abstract:

IFO was recovered and can reach OBSERVATION state.

What I did:

1. Adding a gain of factor 2 for ETMX_NBDAMP_L3 filter to stop oscillation around 5Hz.
2. Adding a gain of factor 2 for ETMX_NBDAMP_{L,T}1 to stop oscillation around 2.2 Hz.
3. Performing initial alingment of XARM and PRMI to recover the IFO alignment.

Note:

I'm not so sure the change of gains of ETMX_NBDAMP_{L,T}1 during the lock acquisition.
So, if the lock acquisition is not stable with the current condition, it is necessary to turn on gains of 0.5 after reaching PRFPMI_RF_LOCKED state and turn off when IFO lose lock.

After the Ushiba-kun adjustment on 31st Dec on several controls (will be reported later), the IFO could reach PRFPMI+DC until 0:00. Around 0:00, the PRFPMI_IR_HANDOVER was possible. However, the IFO became unstable again and could not reach PRMI_3F_LOCKED, possibly because of 1Hz and 2Hz motion enhancement in the EX tower, as shown in the attached photo. 

Now, LSC_LOCK_Guardian was set at DOWN.