I thought it might have something to do with the order on the Firewire chain. I changed the order of the drives but there was no change. I unplugged the drive from Firewire and plugged it into the USB port. The temperature status on the drive changed from Hot to Warm — but still not “OK”.
I changed the order in which the drives are connected to my system. Sure enough. The first drive is always OK. The second drive is always Warm. And the third drive plugged in is always Hot.
So at this point I chalk it up to yet another problem with the WD Drive Manager software. This hurts my already low opinion of this software.
I plan to call WD tech support in the morning so see what they have to say.