Run Powermax HDD s/w V 4.06 (I think it's the latest) on the Maxtor to
be sure, if it does not find a Maxtor drive it's a good bet it's dead,
sounds like it has died, they all die eventually, just some go faster
than others.

One of my systems on raid was running 2 SATA 80Gb drives, one that was
replaced died within one week from brand new, took em 3 months to
replace it.

It's WD-JB's or Seagates for me now.