Hi, thank you for contacting JustAnswer.com. My name is Russell. I will do my best to provide the right answer to your question.
There is not adjustment lever, and if print is blurred, that's not necessarily what will solve the problem.
Remove printer cover and remove the ink roller.
Install the paper roll and feed it until it comes out the front.
Hold an old toothbrush lightly against the printing wheel, and press the [up-arrow paper-slip] button to clean the printing wheel off.
Then install the ink roller and the printer cover again, and see if printing has improved.
If it has not, your calculator will need some part replaced, or need to be serviced.