What would cause a regular pattern of bad sectors?

[Terry Stewart]

Hi guys,

Ive been extracting data off a 3.5 inch windows XP-formatted floppy disk
with many bad sectors.  The odd thing is it's always the same bad sectors
on every track.  Such a 3, 8, 12 and 17.  Once or twice it might be just 3,
8 and 17.  Or occasionally 3, 8, 9 12, 17.  This patten is the same for
every track.  It's  (more or less) always the same sectors that are bad.
Why?  I can't believe natural degredation would be so consistent.  Anyone
have any thoughts?

Terry (tez)