hi Sam, i think you have solved it! Needed to point the "unknown" medium changer at the drivers from above download, then reboot but now showing as IBM totalstorage 3573 tape library and 24 slots in Acronis! Woohoo nice to start to see the end of this project :)
As a side note, we have old tapes to dispose of - i cant see a way of "formatting" the tapes - is there a CLI to the tape unit?
Many thanks for your help :) Paul