My NEC 2500A can read unscrached disks without difficulty but older disks which have had a hard life it can no longer read.
The same old disks, however, can be read without any problem in my 1620.
I have just updated the firmware on the NEC from 1.07 to 1.09 which has helped but not solved the problem.
As far as I can tell either (a) the NEC is getting old or (b) the 1620 is better in the sense that it can read poorer quality disks.
As the NEC can still read undamaged disks I'm inclined to conclude that the 1620 is simply a better drive.
what do others think ?