Good Or Bad Hdd?

Hi all.
I have a WD 2.5" SATA HDD that I have been attempting to clone to.
My TalkTalk You View box, a way of recording and watching free view channels here in the UK, failed so out of curiosity I wanted to find out if I could 'fix' it.
My nephew had a working TalkTalk box he wasn't using so I factory reset it and used that disk to clone from.
I am using Mini Tool Partition Wizard.
There are 6 partitions on the source disk.
The Wizard appears to copy the first 5 but fails on the last declaring the whole disk 'bad'.
As in I end up with a single partition greyed out and the words 'bad disk'.
So i ran the wizards surface test and all was fine.
Then I used WD's disk checker and it passed the quick 5 minute test and then the 3hr test.
Out of curiosity I bought a second hand WD 320gb HDD.
It cloned perfectly.
The wizard is obviously capable of cloning these non windows file systems so it's not that.
So, the question is, are the tests I've ran reliable?
BTW, the cloned disk worked in my failed TalkTalk box but I'm still curious as to why the original HDD is passing all tests but wont clone.
Cheers.