After the removal of 12 bolts from the Table top balance masses (to add viton dampers) we expected needing to replace that lost weight.  We added 3 D071201 (0.3lbs total) to the NW corner--see image.  Betsy removed some more teflon stuff later and we see almost no effect from that change, it was small and fairly uniform in distribution.  ISI CPS vertical readings are a few hundred counts, zero is perfect on this HAM and well under the 2000 cts absolute requirement.  Lock/unlock differences are essentially unreadable; this ISI locks very easily.

Concern though about this added mass: The masses are secured in place with a couple 1/2-13 nuts on the long studs.  There is a recess into which the mass is pulled with the tightening of the nut.  It actually bends the mass in the middle where it is unsecured.  It is light but if there is an unwanted resonance from this, we need to scheme some mitigation: something behind it in the middle to prebend it, a bushing in the well to keep ends from being pulled in...