20 Most Recent HP COLOR LASERJET CP 3505 N PRINTER - Page 3 Questions & Answers

I'd recommend doing a thorough search with a flash light. You also might need to do some minor dis assembly to find pieces of paper. Another suggestion is to clean the paper path sensors with canned air. Lastly check all pick up rollers and make sure they are textured and have no smooth or bald spots. #1 cause of jams is bad rollers.

Turn the printer around and lift the flap behind the paper tray. If you have a flashlight, get it. You want to watch the action of the paper pickup roller. By observing to see if it is rotating, slipping on the paper or whatever, you should be able to determine why the paper isn't feeding. A lot of times, it is as simple as the paper backstop has slid back and the roller can't grab the paper that is 2 inches out of reach. Since you've replaced the tray and paper, I would think you might have noticed that. Is the paper moving out of the tray at all?

Here is a users guideI think pages 38-40 will help youhttp://www.scribd.com/doc/49763575/HP-CLJ-3000-3600-3800-CP3505-ServiceManual

Something is wrong with the yellow cartridge.
pull the yellow cartridge, and make sure transportation strip got fully removed, give the cartridge a good shake, and reinsert the cartridge and try the band test again.
If you still only get magenta and cyan and combinations of them, return the yellow cartridge for a replacement.