Starting Monday the HAM3 HEPI was unlocked for the L4C leveling.  Each corner is relocked during that corner's leveling work.  As the work proceeds there is invariably some position change but the process is done intended not to move things.  It works pretty well with most horizontal changes counteracting one another in the end.

At first unlocking, the HAM HEPI (& presumably the ISI and Optical Table Payload) moved a small amount:
<1mil X or Y and < 1urad Rz.  There was a drop of the platform of 1.1mil(0.0011") the four corners dropping close to the same but different enough to yield a 1.7urad Ry but only 0.5urad Rx.

After the last Corner was completed the total motion from the Monday (unlocked) position was:
<1mil X or Y and -3.5uradRz.  The payload came back up 0.1mil and rotated about the X & Y axes each -1.1urads.  This will presumably be the final floating (no DC HEPI drive) when next released.  Who know what actually having fluid flowing though HEPI will do even though it should be unaffected.

The system was relocked and the motion after this (where it will be for some time) is as follows:
Again, less than a mil X or Y and -1.6urad Rz.  The table is a bit higher, .5mils with -2.2urad Ry & <.1urad Rx.

How the heck does he do it? you ask.  Well, the Inductive Position Sensors are 655cts/mil sensitive, by watching the readings while being locked the position can be held to a few hundred counts at worst, and by careful reconnection of the Actuator so it is not stressed.