An FAQ file on the SyQuest web site says that, if you get a -127 error while trying to read a cartrdige, it indicates that the "directory of this cartridge has been corrupted." They imply that you will have to reformat the cartridge to fix the problem (although I would certainly try Norton Disk Doctor first!).
Up for a challenge?
Put yourself to the real tech test by building your own virtual-reality headset with a few household items.