Is there something I can clean on my HP Laserjet 2600n. I've done the recalibration and things that are built into the menu system. The colors appear faded, especially red. There's an echo-type of racing stripes down one side of the page. The color cartridges are new, but that has not solved the problem. Any suggestions?

Before processing the elighment, ensure that all cartridges are genuine one. In printer menu >go to 'system setup' enter>"printing quality" enter > "calibrate color"..enter...
after completion of the calibration check the quality of print..

check the supply status, if its good perform calibration, if not satisfied go to menu-quality-increase the density of each cartridge then check the quality,
if you are tec guy: if print quality both sides lighter, middle is normal open laser scan assm, clean reflect glass with ear buds/ smooth dry cloth/ leather cloth then check the quality ensure that not to touch any factory align settings...senior professional only perform this activity, strongly not suggested to juniors/ hobbyists..

same as me, I got reduce this effect printing in normal paper as if i where printing transparency paper. The background is lighter now, but still appears.
The other thing I test, printing a blank page it was that with a glosy photo paper with the gloss side to the back i dont get any background. So i suspect it has to do with the tansfer belt ETB rollers.

Hello jagdishgolas!
Theres a few things you need to do first to determine what its causing the problem
Here are some steps you can follow:
1) Print a Supply status report (Main Menu > Reports > Supply status)
If you still see the shadowing is on this page we can tell that the problem is not on the computer
Check toner level on this supply status, if its showing lower than 10 % i would recommend to replace the cartridge
2) Run 3or 4 Calibrations in a row (Main Menu > System Setup > Print Quality > Calibrate Now)
3) Run 2 cleaning modes ( Main Menu >Services > Cleaning Mode)
4) Access the secondary service by hitting the checkmark and the cancel button at the same time, then hit the checkmark again
Under the secondary service look for "Clean Belt" anr run it twice
Try printing again

Heres a link where you can find an Authorized repair center near to your location :

http://h20465.www2.hp.com/GPL/search.aspx?language_code=en&country_code=us&SearchType=SSP

the problem is due to scanner mirror dust.you have to clean the scanner mirror.

Try this: '''Cleaning page'' in the menu, 1,2.3 times. The quality of print out getting better.
This solution is temporary, for a few pages in one day. 
If the printer is used with high intensity, there is necessary to change the Fuser Unit for HP Colour Laserjet 2600/n (200/240v) Part Number: RM1-1821-240CN or Fusing Assembly – RM1-1820(110/120v)

transfer belt or fuser faulty

try the clean heads and alignment in the print manager..

First of all clean the contacts in the printer for the magenta cartridge, if there is no improvement replace the magenta cartridge, if that doesn't work come back to me

Which color is this line? Try changing respective cartridge..