DDS3 Tape Errors and Format

I am having a problem with the DDS3 Tape format or possibly the drives
that support this standard. Maybe someone can help me understand and
suggest some solutions.

About six years ago I purchased a Sony SDT7000 tape backup drive. I
used this for a couple of years but then had to have it repaired a
number of times. On the second repair I purchased another Sony drive
only this one supported the DDS3 format, an SDT9000. Everything
worked well for a while I even had both drives working at the same
time. About three years ago the older drive failed so I discarded
this unit and started using the DDS3 drive exclusively. About a year
ago I began having trouble with this drive. I could not read some of
the tapes that were previously readable.

At this time I purchased another SDT9000 DDS3 tape used from Ebay.
This unit worked for a few month and then quit reading tapes. I then
purchased a Seagate drive and am now getting errors while trying to
read tapes. I have since even tried an HP tape drive. When I load an
inventory the tape the tape ID number shows up. When I try t catalog
the tape I get the error "An inconsistency was encountered on the
storage media in HP-Tape."
The tape drive then reports a blank tape in the drive. Could the tape
be changed? I locked the tape write tab. The data should still be on
the tape, right?

Is there any possibility the data is on the tape?

Any suggestions for understanding this problem and or correcting it
would be appreciated.