After my discovery in this alog that the phase and gain margins were pretty tight on HAM2, I did a bunch of olg measurements on HAM2&3 and tweaked the loop gains and boost filters to reduce the gain peaking around 40 hz. More or less all DOFs on these chambers had ugfs around 35hz and phase margins around 5 degrees. Kinda suprised this was stable, I haven't looked at these in a long time. I do wonder if something is funky with the measurement, but I don't know what that would be. Attached image shows one of the worst, the Z dof on HAM3. Blue and yellow are the new loops gain and sensitivity, red and purple are the old loop. The filter changes might make things slightly worse in the 10-20 hz region, but that should be somewhat compensated by the HEPI to ISI feedforward. Should improve the  30-40 hz motion somewhat though.