Based on the matlab tf measurements taken after coil balancing on SRM SR2 and MC2, and in order to have a physical idea of what's happening, I calculated the DC coupling between longitudinal motion and test mass angular motion for the three stages of the three HSTS suspensions. The results are summarized in the attached spreadsheed, and the numbers in the table are from the transfer function measurements at 0.01Hz (7 averages using schroeder phase drive), and assuming the coherence was good. The transfer functions results are summarized in the second attachment.

To note from the results :
*Length to pitch coupling is roughly ~2rad/m and length to yaw is ~1rad/m.
*M2 length to M3 yaw coupling of SR2 is higher because of the broken actuator.
*M1 length to M3 yaw as well as M3 length to M3 yaw has a different phase than the other sus tested.

The plots can be generated by using the script living in trunk/HSTS/Common/Matlabtools/plothsts_matlabtfs_cross_levels.m
The matlab tf results can be found under /ligo/svncommon/SusSVN/sus/trunk/HSTS/{optic}/{level}/Data