I have seen these drives lose the partition on them, unfortunately when you create a new partition on them your data will be lost, I am not sure as to why the partition disappears but as soon as a new partition is put on them they seem to work.
I also opened them with no ill effect in this regard, they seem to work fine after been opened, so check to see if the drive still has a partition on them if not new one should fix the problem (caveat been the drive will not have any data on it if this is the case)
I have seen these drives lose the partition on them, unfortunately when you create a new partition on them your data will be lost, I am not sure as to why the partition disappears but as soon as a new partition is put on them they seem to work.
I also opened them with no ill effect in this regard, they seem to work fine after been opened, so check to see if the drive still has a partition on them if not new one should fix the problem (caveat been the drive will not have any data on it if this is the case)
Good luck
Doug