Also, the data sheet for the disk drive states that the highest drive number should have a termination resistor pack installed. This MUST be removed from the other drives.
I've still not been able to get a second drive to work. CONFPROG seems to be configured correctly, but when I try and mount the second drive - "INSTALL 0.2" I get an error "DISC ERROR READING INDEX" and the system just hangs. I know the second drive works as it's just been formatted and had an operating system installed and will happily boot a system if it's set as drive 0.
I'm missing something... but I don't yet know what... yet.