HP Envy 5055 won't print or copy in black ink, even though it says the black ink cartridge is fine

[emilys4]

I have an HP Envy 5055 that is off-warranty. It won't print or copy in black, even though it says the black ink cartridge is fine. I tried printing alignment and other trouble-shooting pages, but without the ability to print in black, this doesn't work!

[8lives]

Get a plastic dish and put 1/4" of hot water in it.  
Use rubber gloves.
Remove the black cartridge and put the ink printhead down into the water.  
Soak for few minutes, then remove. 
Touch the printhead to a paper towel and you should see a black line.
Repeat the soak procedure of required.
Clean/dry the contacts with a lint free wipe like a coffee filter.
Install back in the printer.
Try printing.