Problem(s) Encountered:

The Andor camera failed abruptly from one frame to another -- the frames looked like white noise (not zeros).  We had been using the 2x gain; switching to 1x gain solved the problem. 

Solutions:

The two slit-viewing Andor CCDS have now been sent back to the vendor for repair (one has an issue with the 4x gain preamp and the other has a potential vacuum link, limiting the cooldown range).  This camera is set to be used next month and so cannot be returned to the vendor again (yes, this is the one that was sent back in February due to an issue with its 4x gain preamp) until at the earliest, 07/11.  In the meantime, it should still be operational at the 1x and 4x settings.