Hi, I have an Epson Stylus

Hi,
I have an Epson Stylus 4000 printer at home. I had no problem printing high quality prints untill now. I thought that my nozzles were clogged (I haven't use it to print for a several months), so I performed deep cleaning, head alignment twice and although there are no error massages flashing any more, when I print the check pattern, every color is clean except the Mate Black. On the pattern test print this color looks like it's almost checkered, symmetrical pattern mostly black but with a slivers of wight between. Also when I print a photo that has a lot of black areas in it, the black is not solid, but I can see a vertical lines, where the color is not totally black.

Anyone can help?

thanks,
Renata