The unit is not printing dark black anymore it is a light gray print out.

what operating system?

Under your printer preferences there is a way to print gray scale. SO even if your image is in color, it will print black and white. Every printer interface is different, but when you go to print, there's usually a properties or setting button that will bring you to another page from the initial print menu. here is where you would choose gray scale.

If you try for black with only a color cartridge, it'll come out a dark green or blue color. Or on some cases, it will tell you it's out of black and you can't print. Most HP printers need at both cartridges in the printer for it to print.

This solution is unconventional but it worked for me. The black roller on my MFC had irregularities on it and was creating horrible printouts. I pulled out the drum and cartridge and cleaned the large black roller. I used furniture polish to make the roller very smooth. Now it prints really nice.

Maybe it's low on ink or you need to run a cleaning cycle. Try printing the test pattern and look for any missing lines or streaks.

Don't put your e-mail up for hackers to send you a virus!
Try to print from another program. It can't be as obvious as low(or completely dry) black cartridge could it? worth a shot? You can make a dark grey from the color cartridge just not dark black.

Take it back if it is new. If you've had it for a while and it's been sitting unused there may be dried ink in the print head. A visit to the Lexmark website might be useful for any troubleshooting. Good luck.

It si not possible because the %darkness of the black ink and the black toner. The first is near 93% black and the toner even at ***** eye looks dark gray less than 90% black.

There are a few possible causes for the light print.

The first is the easiest to try and least expensive.

If you actually had a bad toner cartridge, and the toner was not making its way down the toner tube to the developer, then you may be able to fix the issue by simply doing a developer cleaning on the black developer. What this actually does is force aggitator to move toner down the tube into the developer. You can activate this from the maintenance menu.

If this does not fix the issue, then more then likely the black developer unit itself is defective and needs to be replaced.

Unit could be in Econo mode, or a bad toner.

Try to change toner cartridge, I had this happen with my old laserjet 5, and it was a faulty cartridge on mine.