HP 220240 - Manual (Page 163)

7.1.2 Cleaning the Primary Corona Wire
The primary corona wire is located inside the EP-S cartridge. A dirty
primary corona wire can cause black streaking to occur on the paper, and
should be cleaned to correct this problem.
1. Be sure the printer is not printing and the display reads
00 READY.
2. Press the power switch on the back of the printer to the O (OFF)
position.
MLO-005117 (Figure 7-7; 15 picas)
Maintenance 7–7