Better get confirmation on whether a Casablanca drive is Amiga readable from a (previous) Casablanca owner before you fry it =).
Either way, hooking it up to a machine running Linux and using the dd command to make a bit-by-bit image of the drive might also be a solution:
http://en.wikipedia.org/wiki/Dd_%28Unix%29At your own risk though

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Isn't it possible to add a second drive to the Casablanca itself?