The only article I can find suggests to clean the printhead and you have already done that. So I would recommend you call into the Support Department for more help. 1-800-821-2797.
I'm getting vertical lines when printing, I've printed the repeating defects page and it doesn't seem to match any of the guides. It's only happening with cyan and yellow. I replaced the toners for both colours as they were coming to the end of their life. I've also replaced the drums as they were only on 9%. I've cleaned the printhead lenses. I've not been able to replace the IBT or BTR as they are on back order at the moment, but both are showing fine in the control panel. I'm not sure if it would be either of them as this is only happening with the cyan and yellow? Any help or ideas would be greatly appreciated.
Thanks in advance!