What am I doing wrong ? Disk Media Test

[Vipersan]

Are you cleaning the heads before every time you do the media test?  You need to!  I am guessing the heads are very dirty.

Indeed I do Jim ..
More likely crap on the disk surface than the heads themselves...and the constant revolutions with heads in contact are cleaning the disks themselves.
not a desireable approach but has got me another 10 useable disks.
rgds