I have a DuoDisk where drive 1 works perfectly, but drive 2 does not respond. No motor movement, activity LED doesn't even light. If I plug the second drive mechanism into the analog board as if it were drive 1, it works perfectly, so it seems like xomething in the drive-selection logic on the analog board isn't working right.
Is there a likely culprit for this behavior, and how should I start diagnosing?