Today, we suspended the ITMy glass PUM from it's loop - the pitch error was better than the metal hang (!) at ~400 uRad (note, better than ~1 mRad is the spec).  Prior to the pitch look, we spent a fair amount of time setting roll correctly.  The tolerance for getting the clocking of the mass correct is ~0.25mm which proved a bit difficult to set manually with the mass sitting on TFE caps.  We overshot a few times before settling in at having the prism-to-prism height diff off by 0.2mm.  We determined that the ergo arm would not have helped us since we had to push the TFE lower stops up for a little loop slack, roll the mass a fraction of a mm, and then release it to hanging for a reading of the pitch with the theodolite, a very iterative process.  This would have taken hours with multiple pump-downs of the ergo arm, likely not yielding better results than us doing it "by hand".

Since the loop looked good, we proceeded with installing the ITMy test mass into the sus structure.  We stole the base from the split rotation tooling and mounted the ITMy LS/LSAT/Weld Trolley on top of it such that the ergo arm legs would fit underneath while installing the optic.  The install went well, right through the open ring heater from the back of the LS structure - the ears only have a few mm of clearance with the structure, but it went well with 3 spotters.

Pictures to be posted on ReSource Space shortly.