It is known that if the little test-masses in the STS-2s get too far from center, then noise of the instrument gets worse.
They should all be in the -2V -> +2V range, and one of the End-Y masses might be at -8 V.

Because we are fortunate, Ben Abbott attached the mass-location-monitor to our ADCs.
see pg 11 of the BSC SEI system wiring schematic
https://dcc.ligo.org/LIGO-D0901301
The UVW/ mass positions are being send to ADC 3, chns 20, 21, 22 (for nums 0-31)

Because we are knuckleheads, we do not seem to be monitoring these channels.  
An integration issue has been filed: https://services.ligo-wa.caltech.edu/integrationissues/show_bug.cgi?id=1148

Because we are committed to excellence, all the inputs from the ADC are saved as EPICS records.
I think that the epics channels for the end station are
H1:IOP-SEI_EY_MADC3_EPICS_CH20
H1:IOP-SEI_EY_MADC3_EPICS_CH21
H1:IOP-SEI_EY_MADC3_EPICS_CH22

the other STSs should be at
   - end X -
H1:IOP-SEI_EX_MADC3_EPICS_CH20
H1:IOP-SEI_EX_MADC3_EPICS_CH21
H1:IOP-SEI_EX_MADC3_EPICS_CH22

and for the 3 in the corner station

S1:IOP-SEI_[B1|B2|B3]_MADC3_EPICS_CH[20|21|22]

(or maybe it is B6, but I don't think so)


I looked at the channels for End Y, and it seems that the STS-2 at End Y needs re-centering.

It would be smart to 
1) watch the monitor channels when you mash the re-center button. If they are the right channels, it will be very clear.
2) check the other sensors, too.