Hugh R., Eric A., Jeff G.

We believe we have found the solution to the odd GS-13 behavior from the transfer function measurements.  After several failed attempts to implement the damping loops, the path from each GS-13 to the feedthrough board was traced to see if any cables had been swapped since unit_1 testing. 

 Hugh and Eric noticed the "clean side" of the feedthrough for H1&V1 had been swapped with H2&V2. Since both GS-13s for each location (i.e. 1 & 2) are on the same cable up to the feedthrough, H1 & V1 were being mistaken for H2 & V2 and vice versa.  After the swap, a quick test from 200-800Hz showed the Horizontals and Verticals were fairly close in magnitude in this bandwidth, similar to unit_1.  Full measurements of the full bandwidth to be posted soon.

Shortly thereafter, the damping loops were implemented successfully with gains of -1.  I will set up long collocated and coordinate Transfer Function measurements for tonight.