CDC Sabre 8" SMD blues

Hi folks, I recently picked up a Symbolics system built around an 8" Control Data Corp. Sabre hard drive. Some files read when I show the FEP directory listing but many show as "Error reading file header, wrong pkid read" which I assume is some sort of FEP FS integrity check. In short, the drive becomes ready and much of the data appears still there, but I have some brand of consistent read errors that preclude the machine from booting. It's not a software issue as the machine was deinstalled in a working condition. Anyone familiar with these terrible drives? Am I totally up the creek? I tried a couple different orientations. Thanks, - Ian Sent from Outlook Mobile