LTO3-Error

I have a HP Ultrium 3-SCSI Tape drive.

It behaves as seen on the video:

HP Library and Tape Tools - 4.15:

- "Health" gives the following directly after trying to insert a tape: http://666kb.com/i/cbklue3yunxdu6d50.gif
- The same error i get at Test / Device Analysis.
- Klicking on "Health" or starting "Device Analysis" again claims that everything with the drive is OK.
- All other tests which do not need a tape say that the drive is OK. For example: "Device Self Test": http://666kb.com/i/cbkm87ddt05d26io4.gif
- The tests which require a tape of course cannot be executed.

I already disconnected and reconnected all the plugs within the drive and checked carfully for other visible defects. I am an electronics professional.

Any qualified (!) hints what could be the cause of this failure are very welcome, as also are URLs from where i can download a Service Manual for this device. (Not Users manual, but Service manual).

Thanks in advanced, best regards :-)