Problem(s) Encountered:

After taking a list of Xe lamp spectra, I clicked the finder  out  and the  Xe  button (to turn off the lamp) on the MIS xmis2 panel. This led to the wrong message finder mirror = Xe  instead of  finder mirror = out . Then I checked the status of finder by targeting a standard star with the telescope and moving the guider probe to a bright star, but neither guider camera nor slit viewer showed stars. I tried cycling finder  in  and  out  a few times, and restarted the MIS xmis2. Later the guider camera could see some stars but with possible obscuration. The slit viewer still
could not see stars. It seemed that the finder was not in the right place. I homed the telescope and closed the dome at mid-night.

Solution:

For some reason, slit-viewing camera was set to 2x2 binning, which was saturating the detector.  Had to restart MaximDL (slit viewer) in order to see the slit with the flat lamp.  Same thing for the guide camera.  Perhaps there is a reason why one would want to bin the guide camera, but I don’t think this is common.  
Checked today and verified that the finder is moving IN/OUT as demanded.