Problem(s) Encountered:

While opening for the night, got to the mirror covers opening then the error mirror mirror timeout came up. Immediately after this another error I have not encountered nor could find in the archives repeatedly popped up on the TCS log 'error mirror mirror both open and closed'. I refreshed the 1.3m control panel, this had helped before with the first error, restarted JskyCalc etc but the same messages continuously appeared. Had to get help from Eric. He ssh'd into the system, tried similar things at first then eventually had to reboot McGraw, re-zero ra and dec etc. Once this was done, the error messages stopped appearing and things continued as normal. 

Solution:

It appears that this issue was ultimately hardware-related.  The original “closed” limit switch (Omron D5B-5021) was degrading and starting to fail.  This limit has always been problematic in mechanical design and how it is used in this application.  It is also quite expensive (~$100 for a replacement).  I devised a way to wire in and mount a standard contact limit switch (D44Y series) so that it functions equivalently to the old.  This should be more robust, easier to replace, and far less expensive (~$10 per switch).  Also, I have spares on hand already.