Has anyone seen a video / photos showing how to clean the printhead please? Not having done one, not sure where to start - I know how to take the head out but what to clean etc. is a mystry...
You don't mention what kind of a printer you have. Assuming it's a Canon with separate cartridges for each color, you can see my recommendation on cleaning the printhead at this link:
I do not recommend taking the printhead out of the printer. Canon printers are designed to clean their own printheads but sometimes they need a little help. There have been many cases, including one of my own, where a printhead has been damaged by attempting to clean it outside the printer.
In order for the printer to clean its own printhead, it must have a clean and working purge unit. The above link takes care both of making sure the purge unit is clean, it also helps getting the printhead clean. Please follow those instructions and let us know how you do.