My Linux machine did not even acknowledge the presence of the new drive after it had been in the Humax which suggests that either the caddy does not see a formatted drive with no files or that the drive was not formatted by the Humax I will try the drive "internally" in the Linux machine to see if it is detected then. I obviously cannot cause the Linux machine to format a drive that is not detected when the USB caddy is plugged in. Last week I put a brand new drive into a netbook PC and installed Mint 18.3 onto it from a USB boot stick. I don't know if the machine detected the blank drive before the ISO image went across to it....
I am running out of unformatted or blank disc drives to try!
Time to get the lid off the linux box...
Rans6.......