Cleanup slot

do you mean to just add the tape 000079L5 to the retired media sets and then remov it? can we again  reuse the tape 000079L5?

Yes, this is just a trick to delete this tape from the BE database temporarily.  It doesn't change anything on tape itself.  The tape can be used again, simply by running an inventory job.  If there is no valuable data on the tape, then also running an erase job may be helpful.  If there is data on the tape that you wish to restore, then you need to run a catalog job.

I recall that there were issues in the past with swapping media, do you have all the paches installed on your BE 15 server?  This may be an issue that was already fixed.  Please run LiveUpdate within BE to get all the patches.

I believe that your library should have a web interface available for management.  Does it show the cleaning bar code in slot 16?  If the library interface doesn't show the correct bar code, then it isn't surprising that BE doesn't have the correct info either.  You might be having issues reading the bar code on the cleaning tape.