The plot thickens.
How long had you the MyBook before it went belly up?
I forget, honestly. It was long enough that I was relying on the drive, but not long enough that I found it an acceptable failure, by any means.
On the bright side, once you know the secret knock, the case opens pretty easily: If you look at the four recessed spots on the big side where the rubber feet can go, just like on Sesame Street, one of the things isn't like the others--it's an adhesive circle that hides the screw. After that, there's some manhandling to do, but it's all obvious, at which point you can yank out all the plugs and replace them.
My non-engineering brain thinks that the Western Digital circuits probably aren't tolerant to power variations, so it burns out easily. On the other hand, on sale, the external drives are cheaper than most internal drives, so that's not too bad a deal.