Lexmark 302 - Manual (Page 199)

Customer Responsibility
Discuss the importance of the operator knowing what is and what is
not
customer responsibility. The customer is responsible for
maintaining, removing, installing, and ordering the following:
Ribbon cartridges
Paper.
Also, the customer is responsible for following the instructions in the
problem solving sections of Appendix B, “Problem Solving” before
calling for service. For example, if the characters in a printout have
missing dots, the customer should look up the problem in this
chapter.
Appendix A. Training Guideline A-7