HP Color LaserJet 2600n

you need to shake the black toner, remove the toner, or maybe it need to replace already

You likey have a bad CYAN cartridge, that is the first thing you want to replace.

The cartridge is missing contact from the drum to the ground. When this contact is missing, the charge from the the laser exposed areas on the drum cannot disappear and the result is lack of image.
Remove the cartridges and compare the connecting pins of the nest for the black with other nests. One may be bend and loosing it's contact.

It a problem with printer fusing assembly. so you can checked it from service center.

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

There is an override sequence and it works well. Press the select button (checkmark) to indicate Main menu. Press right-arrow (RA) to select System Setup. Press Select , then RA to Print Quality, Hit select. RA to Replace supplies and hit Select. Now, RA to Override Out and Select. Confirm with Select again. Your 2600n will now run even with an empty toner cartridge.

Are you sure that none of the other colours are empty? If they are then this could be the problem

an allignment need to perform on printer with proper placement.

This is caused by toner contamination in the laser scanner unit, it is quite a complex job removing and cleaning the laser scanner. I would suggest you contact HP regarding the repair.

It's normally caused by dirty scanner mirrors, the machine will need to be dissembled, the laser scanner unit removed, taken apart and the mirrors cleaned. Unfortunately it is quite fiddly getting the scanner unit out, but this is a very common problem for the HP colour laserjet 2600's
If you want the service manual it can be downloaded from the following link free of charge http://www.eserviceinfo.com/equipment_mfg/HP_22.html