That's fixable, Scott. Strip down the drive, clean it and relubricate it. If that fails (which is possible if the mechanical parts are worn), swap the drive mechanism for the early series 3.5" -- mechanism part number can easily be found on the web. The really important thing in the UniDisk is the drive controller board.
Fix it while you can remember why it is problematic. You don't need it for the IIe workstation card for most software, but it is too useful to lose.
Is that page really so old? At the time, it would have been hosted on Demon and written on an LCIII with *trumpets blazing* a IIe workstation card.