Epson EQUITY 3865X/20 PLUS User Manual page 207

Caution
Do not attempt to remove the math coprocessor yourself.
Contact your dealer for information about a special
extraction tool that is needed to remove it.
2. If your math coprocessor is listed as installed in the
Setup program but still does not seem to be working, check
the manual that came with the math coprocessor for any
additional procedures you may need to perform or any
troubleshooting information.
3. If you are still having trouble with your math coprocessor,
test it by running the System diagnostics program on your
Reference diskette. See Appendix C for instructions. If your
math coprocessor came with its own diagnostic program,
check the documentation that came with it and run those
tests also.
A-28 Troubleshooting