Hi, I'm Sudipto. Welcome to JustAnswer. I'm reviewing your question now, and will post back with your reply ASAP
The problem you are facing can be caused due to few reasons, one if the ink is low, two if the printhead is clogged, three if the printhead is defective , four if the timing or encoder strip is dirty. Now, as you have not mentioned anything about printhead, cleaning, I will first recommend you to clean and deep clean the printhead and reply me back.
You can follow the steps from the links below to do those jobs.