Working with WD support now, they have me reinstalling the firmware. I’ll post how that goes…
As for checking temperature:
Putty to WD MyBookWorld (must have SSH enabled from the web interface)
For drive 1 use:
smartctl -d ata -A /dev/sda|grep Temperature|cut -c 5-28,88-
For drive 2 use:
smartctl -d ata -A /dev/sdb|grep Temperature|cut -c 5-28,88-
These should be very close, i.e., within one degree. They should never be above 55 C.
As for the fan (I can not be held responsible for damage that may occur attempting this, this is my experience only),
I have a small 2" 12v fan that I bought at Radio Shack some time back (they still have them). I cut up a spare USB cable and found it had red, black, white, and green wires. I connected the matching red and black wires on the fan and USB cable and tested them on a USB travel charger (Didn’t want to burn my MyBook). This worked to spin the fan at a good speed. I put the fan on the top center of my unit using some double sided tape so that it “pulls” the air out to the unit in the same direction as the natural convective heat rising. I can’t hear the fan and as stated, it cooled the unit at idle by 11 degrees F. Temperature is life in electronics.