Strange - it's almost like it kept the old errors, even though there's new drives in place.
Can you force a consistency scan from within the RAID console?
Yes the consitency scans in my first post were from the console.
To confirm the errors on the old drives I ran Spintite which confirmed that each of the removed HDD are indeed having difficulties. One is in fact completely dead now.
Does Spintite show any problems with the new drives you put in?