I got a new 755A replacement drive that worked for over one month now.
Since a couple of hours all discs I burn (Nero) give the following error:
write error burn process failed
The DVD is readable after that, but the last file on the DVD is corrupt.
Also I don’t think the leadout has been written on the discs.
Using the same brand media as yesterday (and earlier today): Plextor, Verbatim, Platinum and DataWrite.