Epson Epson - Manual (Page 153)

If reinserting the diskette does not solve the problem, insert the
diskette in another diskette drive of the same type. If you can
read the diskette in a different drive, your drive may be faulty.
The diskette is the right type, but you still see an error.
Check that the diskette is not write-protected, preventing the
drive from writing to the diskette.
Make sure the diskette is formatted. See your operating system
documentation for instructions on formatting diskettes.
The system may have the Diskette access security option
in SETUP enabled. If you entered a User level password when
you started the system, but this option is set to a Supervisor
level, you see an error when you access the drive. See “Using
the virus protection features” in Chapter 2 for more
information.
You may have a defective diskette. Try copying the files from
the bad diskette to a new diskette.
Something is wrong with the data in the files.
Run ScanDisk to repair the files. You may also be able to use
special utilities or diagnostics to solve this problem.
Diskette Drive Problems
A newly installed diskette drive is not working properly.
Make sure you have installed the drive correctly and check all
the cable connections.
Troubleshooting 7-9