Maybe there is also a TF of the monitor point of the loop?
Something is iffy about #99fc2933. Looks like the OLG doesn't every cross 0dB, which is bad.'
I think more info is needed about the TF of the in loop signal to the monitor point. The BNC on the front panel isn't exactly seeing the in-loop signal there is a resistor and voltage divider set up there (see, https://dcc.ligo.org/DocDB/0004/D040105/001/D040105-C.pdf). I always though you needed two readout points in the loop to get to the OLG as you need to somehow cancel (mathematically speaking) TF of the monitor points.
I think we need to take TF from both out1 and out2 still. Its just they are taken separately wrt to the excitation. I've yet to do the math to work it out though.