Lexmark 302 - Manual (Page 205)

The operator panel setting for the forms device does not match the
device installed. Be sure that the forms device setting is correct (see
Chapter 1, “Setting Up the 4232 Printer Model 302”).
Document Insertion Device (F3):
This is not an error condition. Press Load/Eject to position the form
to the top of form position and enable printing.
1. Press Stop.
The left margin automatically resets to 20 units. See Chapter 1,
“Setting Up the 4232 Printer Model 302.”
2. Press Start.
The operator panel function is invalid or the computer is overriding
the request.
1. Check the operator panel function.
4 PRESS LOAD
5 MARGIN ERROR
ADJUST MARGIN OR LINE LENGTH
9 INVALID KEYPRESS
9 INVALID MULTIPLE KEYPRESS
9 INVALID KEYPRESS
PRESS STOP FIRST
Appendix B. Problems B-5