Followup:

I managed to get the IDE drive to recognize the RLL drive, but for some reason it wouldn't read the data off of it.

What I *could* do is get the RLL drive by itself to recognize the 3.5" drive, from which point doing the DOS backup was a simple matter. Thanks for the tip!

It felt good to get my hands dirty again!

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The opinions expressed herein are my own and not those of my employer.