Problem(s) Encountered: The first issue was that the instrument rotator failed (i.e., the hand paddle in the dome didn''t work). I came inside and tried to issue a command for a small rotation through the GUI, which also failed and sent up an error message that the mirror covers were closed. I verified that the mirror covers were indeed all open. As in http://www.astronomy.ohio-state.edu/~martini/osmos/rotator.html, I turned the power on the rotator box off and on and restarted the GUI. The rotator still didn''t work and gave the same error message. I thought I would close and open the mirrors again, so I stowed the telescope, and closed the mirror covers. However, they would not open again when I flipped the switch. Not sure what else I can do, but at least this happened at 4 a.m. Solutions: Check valve on the compressor got stuck open, causing the compressor to run at full duty cycle.  This overheated the motor, which subsequently went into thermal shutdown.  As pressure bled off, the mirror cover petals could not stay fully open, causing the rotator to balk. Cleaned up the check valve and it appears to be working correctly again.  Also, I tore apart the air transfer line and fittings and cleaned them up as there were some small leaks there as well.   We are looking at finally performing the swap over to the oilless compressor system for the mirror covers and brakes.  This will put the load on a much newer and cleaner compressor, and result in the old compressor being relegated to spare status. Lastly, I showed the observer how to use the N2 bottles to pressurize the system in the event that the compressor fails again.