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Image formation troubleshooting 
159
 
Print is faded or 
you notice a block 
of vertically aligned 
white streaks,
or print is not 
faded, but vertical 
white stripes 
appear on the 
page. 
The toner cartridge is getting low on toner. 
The HP LaserJet 3100/3150 product 
needs to be cleaned.
The paper you are using does not meet 
HP’s paper specifications (for example, it 
is too moist or too rough). 
Toner density setting is not adjusted 
correctly. 
A part of the HP LaserJet 3100/3150 
product is damaged.
The internal mirror or optics are 
contaminated.
The laser/scanner is damaged.
Redistribute the toner or replace the toner 
cartridge.
See the appropriate sections of Chapter 
3, “Maintenance.”
Make sure that the media meets 
specifications detailed in HP’s media 
specifications guide.
Adjust the setting from the control panel.
Follow the steps in “Basic troubleshooting” 
to isolate the problem.
Clean the mirror by blowing air through 
the laser/scanner to remove any dust 
particles.
Replace the laser/scanner.
The document scanner needs to be 
recalibrated.
There is a problem in the contact image 
sensor.
There is a problem in the formatter.
Follow the instructions later in this chapter 
to recalibrate the document scanner.
Replace the contact image sensor
Replace the formatter.
Stains or smudges 
appear as small, 
round, black dots 
on the front or back 
of a page. 
Sometimes 
inconsistent stains 
appear.
The paper you are using does not meet 
HP’s paper specifications (for example, it 
is too moist or too rough). 
You are printing on the wrong side of the 
paper.
The HP LaserJet 3100/3150 product 
needs to be cleaned. 
The toner cartridge is damaged. 
Make sure that the media meets 
specifications detailed in HP’s media 
specifications guide.
Remove the paper from the paper input 
bin and turn it over. (The wrapper on many 
reams of paper has an arrow indicating 
the print side.) 
See Chapter 3, “Maintenance,” for 
instructions on cleaning the product and 
using a cleaning page.
Replace the toner cartridge if 
maintenance procedures do not improve 
print quality. 
Problem Cause Solution