MyBook not behaving correctly with failed drive

I have a FireWire MyBook Studio with a pair of 2TB WD Green drives in it. One of the drives seems to be failing after less than a year, and more worrisome, unless I remove that drive, the whole device is unreachable. Which seems kinda lame for a RAID-1 device. The whole point is one drive can fail and you can keep using it, but not with this WD device. 

Can someone verify, is this not intended beahvior and I may have a failing Enclosure as well as drive? Or verify that this is what WD thinks RAID-1 is supposed to be?

In this particular situation it’s hard to asses if you are unfortunately facing an enclosure/controller failure at the same time as a disk failure.