I have just inherited an HP T4000s tape drive (which appears in the quirk
table => must be know about), but trying various tapes, I either get

st0(ahc0:4:0):  Check Condition on CDB: 0x1b 00 00 00 01 00
    SENSE KEY:  Media Error
     ASC/ASCQ:  Positioning Error Detected By Read of Medium

or

st0(ahc0:4:0):  Check Condition on CDB: 0x00 00 00 00 00 00
    SENSE KEY:  Media Error
     ASC/ASCQ:  Incompatible Medium Installed

This happens no matter what I try eg mt status, tar t,
dd if=/dev/null of=/dev/nrst0, mt erase etc. Any thoughts on what
else I could try? (NetBSD-1.4/i386)

Cheers,

Patrick