HP CP3505dn stopped printing any color

[Camaro4505]

I have an HP CP3505dn that is only printing in black and white and has quit printing any color. Performing a color band test at the printer itself returns only black and grey bands, and color bands are completely blank. Black 66%, Cyan 84%, Magenta 84%, Yellow 84%. I had this same problem in 2023. I tried first by replacing all of the toner cartridges with new HP cartridges, this did not help. I tried doing a full reset on the printer, no luck. Eventially I called HP support and spoke with a technician, and even though this printer is long out of warranty, she somehow was able to help. As I remember she was able to remotely access the printer. I am not sure what was done, however; the printer has worked ever since until approximately a week ago. Now it acts like a black and whire Laser Printer. Even though this is a printer from 2007, I bought it new in the box in 2019 with all of the original packaging and tape still in place. Other than the color being gone again it is still a great printer with only 938 engine cycles. Any thoughts or suggestions on what may be happening and how to correct would be greatly appreciated. Thanks

[Repairatrooper]

Try an engine test and report back. This should produce a page with alternating lines of all colors of toner and if that works you probably have a formatter issue. If it only produces black lines in this test then you are looking for something amiss with possibly the transfer belt. If you perform a half test, opening the door just as the paper starts to feed, you can see if an image is being formed on the drums of the toner cartridges. If there is image then you have a issue with the alienation mechanism that disengages the color portion of the transfer belt when printing only black. If there is no image on the drums then you may have a high voltage issue, although I would expect in that case for the black not to print either. I have seen cases where a faulty yellow toner causes colors to stop printing.

[Camaro4505]

Thank you for reaching out, "Try an engine test and report back. This should produce a page with alternating lines of all colors of toner and if that works you probably have a formatter issue. If it only produces black lines in this test then you are looking for something amiss with possibly the transfer belt. "IT ONLY PRINTS THE BLACK LINES" If you perform a half test, opening the door just as the paper starts to feed, you can see if an image is being formed on the drums of the toner cartridges. "NO IMAGES ON THE COLOR DRUMS, THE NON-TRANSFERED BLACK TEXT WAS STILL PARTIALLY ON THE BLACK TONER DRUM"  If there is image then you have a issue with the alienation mechanism that disengages the color portion of the transfer belt when printing only black. If there is no image on the drums then you may have a high voltage issue, although I would expect in that case for the black not to print either. I have seen cases where a faulty yellow toner causes colors to stop printing. "I WILL TRYING TINKERING WITH THE YELLOW CARTRIDGE, DON'T HAVE A SPARE TO TRY THOUGH, NOT SURE I WOULD WANT TO BUY ONE JUST TO TRY." Any other thoughts on this are greatly appreciated, thanks again.

[Camaro4505]

Update, directly after performing the half test, opening the front door of the printer and inspecting the cartridge rollers, with the black roller being the only one containing text and the partial print being only black, something strange happened. After removing the paper "paper jam indicated" the printer got itself back together and automatically reprinted the PRINT DEMO and now the color is working, and now the engine test is printing all of the color and the black lines. This is how it came back to life about a year ago, mysteriously and then died again recently mysteriously. There must be some component on it's way out just can't seem to pin point it. Thank you for all of your help, any thoughts on what the problem may be?