Epson EL 486UC - Manual (Page 105)

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
If you are using MS-DOS, run CHKDSK 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.
You see a diskette drive error when you start your computer.
Run the SETUP program and configure your system for the
correct type of diskette drive.
The diskette drive is making loud or unusual noises
Contact your Authorized EPSON Servicer or the EPSON
Connection.
Troubleshooting 6- 7