I adjusted the demodulation phase of the REFLAIR_A photodiode in the delay line phase shifter by toggling the physical switches on its front panel.

Right now, the phase is adjusted such that the length signal from the power recycling cavity shows up in Q which is opposite to the usual signal convention. Because the phase shifter could rotate it by roughly 100 deg at 9 MHz which was not big enough to get the I signal maximized for the power recycling signal, I ended up with the Q signals maximized. The adjustment was done by letting the PRX cavity freely swing and taking a look at the I and Q monitors of the demodulation board with an oscilloscope. The attached is a picture of the resultant physical switches after the adjustment. Note that it is set to be the internal switch so that the digital system can not mess it up.