Sorry BH I tried to remove my last post, but then you posted after!
Anyway my thoughts
WD Blue is not a particular range description you can rely on because WD change the goalposts more than once.
I would hazard a guess 1TB 2.5 data drive will be at least sata2. The other drive you mention WD10EZEX is a 3.5 drive, which is not relevent in this thread (unless that was the original drive).
But I agree with most of the other points.
The other thing to try is another power supply that is suitable for the Humax (12V 2A) in case the original one is marginal or on the way out.