In case you want to test the drive in a ML3 you can do a Drive Diagnostic Test.
From the start screen press two times
Enter
Now in the
Home menue select
Maintenance.
Select
Library Tests...
select
Drive Diagnostics...
now you can choose the drive you want to test.
(In that Library is only one Drive available)
For the selected Drive you will find a drop down menue. Here you can find
Power On Self Test (POST).
If a Tape is loaded in the selected Drive the Library will unload it.
After that the test is
Running and the progress information will be displayed.
if all tests passed successful the
Test Status is
Passed.