Epson Equity 286 PLUS - Manual (Page 234)

If you are sure the hard disk has been installed properly and you
have prepared it for use as described above but you cannot access
the drive, review the instructions in your MS-DOS Installation
Guide. Make sure you performed each step in the installation
processcorrectly for your configuration.
If you cannot identify the problem, consult your dealer.
Accessing Data on the Drive
If you have been using your hard disk drive successfully for some
time and notice a reduction in performance, the data on the disk
may have become fragmented. You may want to back up all your
data and then use a disk compaction utility to reorganize the
files on your disk. Contact your dealer for information.
If you still have trouble with your hard disk, you can back up
your data and physically format the disk. Then you’ll need to
reinstall MS-DOS and copy your files back onto the disk. See
“Hard Disk Format” in Appendix C and your MS-DOS
Reference Manual for instructions.
If you cannot access data on your hard disk or you are receiving
read/write errors, the disk may have a physical problem. Contact
your dealer.
Troubleshooting D-15