I started injecting jitter lines in the periscope PZT: pitch at 215 Hz, amplitude 20, yaw 135 amplitude 10, in H1:IMC-PZT_PIT and H1:IMC-PZT_YAW. The yaw line is very well visible in DARM, the pitch line is much smaller. This is as expected, since yaw is the main jitter that couples.
I tried to move the AS_C YAW offset to move the SRC, without any change in the jitter line amplitude, with offsets as large as 0.2.
I then tried to move the OMC alignment. It looks like there is little effect on yaw, but some effect on pitch. Bummer. More on a later alog with a full OMC alignment change.
Actually both PIT and YAW see coherence with DARM, so maybe this is worth some more thinking. The PZT injection is very visible in yaw, but not much in pitch