HI,
Any Print Quality issue with HP laserjets should always start with a "Full Calibration".
Calibrate the product
Calibration is a product function that optimizes print quality. If you experience any image-quality
problems, calibrate the product.
1.
Press the Menu button .
2.
Press the down arrow to highlight the CONFIGURE DEVICE menu, and then press the OK
button.
3.
Press the down arrow to highlight the PRINT QUALITY menu, and then press the OK button.
4.
Press the down
Sometimes it's worth dong the full calibration a couple of times.. If no resolution/fix, then perhaps if you have another CP3525, try swapping the ITB (Transfer Belt).