epson l120 problem in black print quality

Good day guys,

I'm new here and I need help regarding my problem in epson l120. The black ink printout is always has banding. And sometimes no printouts in other area. I try research regarding on how to unclogged printhead but still not working. Can you suggest me on what to do if I have to bring it in service center or there's another way to make my printer back to normal quality print outs?

Thank you.

jeff