HP Color LaserJet 2605dn will not print red at all, black in sometimes work, sometimes doesn't

[ACella]

For a long time my printer will not print any red. I am using an HP Colorsphere cartridge, and I cannot figure out why it won't print any reds. Even the sample page is yellowy. I've reset, recallibrated, "cleaned", nothing helps. Has been this way for a long time. I've lived with it. At $100 an ink cartridge, just not willing to go buy a new one and see if it's the cartridge or the printer... interestingly, even though no red color prints, that cartridge is running low at the same rate as all the others. 

But now...

Recently, my black toner sometimes will print just fine, then sometimes it will hardly print at all. It seems to print fine the first time, maybe even the second or third, then not so after that, especially for multipage documents, if I have to print something more than once. But if I come back later it will print just fine. Or if I open the printer door and close it again and let things reset, then it will print just fine each time. The ink is getting low but there is no error message. 

So here is my question - has anyone else experienced either of these problems and been able to get them fixed? Can anyone guide me as to whether this is a printer cartridge problem or a printer problem? At a $400 investment for all new ink, I am warry about buying new cartridges just to find out the quality of the cartridges is spotty, or to find out the printer is dying and new cartridges won't help. Advice on where to go or what to do? Give up on the printer? Take it somewhere to be looked at? At $550 I think I can get a new laser color pringer, including the ink... 

[east2100]

No red color printed which is faded lense needed to be cleaned.

There are many of them on YouTube jsut keyin HP 2600n.

https://www.youtube.com/watch?v=2Y6gkQL9FM8

But this one not doing good enough because there're another four mirrors down below should be cleaned at same time by using Q-tip cotton.

https://zh.ifixit.com/Guide/How+to+fix+HP+Color+LaserJet+2600n+Fading+Color/43207

http://www.reeves-hall.net/tech-gadgets/fixing-washed-out-colour-on-hp-color-laserjet-2605/

Black printing fine but sometimes not which might be the gear assembly problem.

The gear assembly seats at behind the right cover and there are two soleniids to control them one is for the black color ane the other is for the three colored printing.

It is so called Sticky Solenoids problem.

http://westhillprinters.blogspot.com/2011/12/sticky-solenoids.html

You just need to put a V-shape paper (use a narrow long paper and fold it in the middle of it) into between the solenoid's L-shape & electric-energize to keep the energized & sticky away.

There's no need to clean any sticky thing off.

It'll be done for a long long time enough.

I have done this way on hundreds of printers and it never fails.

There's the 3rd one of the solenoid which seats at left bottm conner when you look into it from the right side cover taken off.

It's for paper input controlled you'd better take care of it at the same time.

After all there were done you can happily use it from then.

Hope it helps.

[ACella]

Thank you so much. That explains a lot. I think if I were braver and had more time I could tackle that and try it. I took my oven apart once to clean in between the glass and it was never the same... getting the printer back together right is much more critical than the oven for it to work right.