I calculated how the DC signals should look like in the Y arm PRMI configuration.

The expected signals are overlaid in the same plot as that of shown in #6313.

You can see there are disagreements between the observed and expected signals in the plot below at around the time when the arm is brought to the resonance.

(expected behaviors)

•  TRY: At the end it should be at 1 (remember TRY is normarlized) and should not go more than that, since the power-recycling is in a weird situation and it is not fully recycling the power.
•  ASDC: It should become brighter at the end because the arm cavity flips the sign of the reflected light and hence the dark port must be on a bright fringe.
•  REFLDC: It will decrease a little bit because the arm cavity and MICH try to suck some amount of the power into the interferometer.