Sorry, I obviously forgot to mention the actual problem

Although it is seeking quite loud while copying, it repeatedly seeks for several times and even louder when it comes to one of the locations where it does what I called "failing", no data is transferred and after some attempts the drive stays busy, not responding to further commands until power-cycled. The locations are reproducable the same, every approx 128MB in the first 2 Gigabytes or something, every 256MB between 2 and 6 GB and as I wrote no faults between 6 and 10GB.
I haven't yet tried whether it has a serial terminal so I cannot tell if or what it reports.