Oki 8810 print head

https://www.oki.com/printing/download/59348501_210042.pdf
(Check the headgap lever position - page #8)

I would think you have broken ribbons cables to the cyan and magenta LED print heads. As all the heads are the same I suggest you swop the black and cyan print heads around and see if cyan prints and black does not. That will prove is the print heads are ok. If they are then the ribbon cables need replacing or they are dirty at the heads. It could be just a case of unplugging them, clean them, then plug them back in again.

I assume your asking how to change the "Print head" power off the machine, remove the ribbion and plastic mask (lifts up) you will see 2 gold phillips head screws. unscrew them both and lift up the print head. push in new print head and reverse the directions you removed.

You need to do s head clean.
This could take 2 or 3 goes but should fix it you will find head clean in the maintenance settings.
It eats the ink so only do as you need.
let me know how it goes.
Regards Craig

If the missing spot is always the same it sounds like a broken pin in the print head. If this is the case you need to replace the print head.

Your printer has a damaged mainboard. Very sorry, for yours is a very good unit. the replacement model is the Oki ML-420, which comes with a 3-year warranty.

Be blessed.

There should be a printer icon in the bottom right corner of the screen on the taskbar. Double click on that to open the printer box. You can also open the printer by going to Start/Control Panel/Printers and faxes and double click on the printer. The print jobs are listed in that box and you can right click on one and select cancel. Or go up to Printer and select cancel all documents or go up to document and just cancel the document that is selected. Just to let you know though, sometimes, however when you cancel a document it can take a long time to cancel. Hope this helps!

you are correct, you need a new print head OR adjust the head gap on the carriage