Thank you for your quick reply!
Seems the problem is introduced when I dd from the old to the new HD.
As you mention there is a mismatch between the size of the two drives:
root@1[knoppix]# dd if=/dev/sda2 of=/dev/sdb2 bs=128k
dd: writing `/dev/sdb2': No space left on device
942+0 records in
941+0 records out
123379200 bytes (123 MB) copied, 10.9626 seconds, 11.3 MB/s
The size of the new sdb2 is larger than the original sda2.
Tomorrow I'll try to copy the files across to a freshly formatted
drive using plain cp rather than the dd function. I'll keep the topic
updated and I will amend the wiki when I have this settled.