After one and a half years of the USB flash drive was dead. Had almost given him after he is a few months just rumgelegen only useless, I have with all imaginable methods trying to revive him. Had him try on dozens of different USB ports and hubs and rumwackeln until I could at least back up my data. The USB flash drive appears to have a wobbler and is therefore no longer usable. Very bad, 2 years ago was not as low part. Since the problem probably often emerges, it seems to be an isolated case but a production error. Have turned to the customer and look forward to the feedback!