I completed tax return and printed forms to mail but then noticed the income (state part year resident) was not correct. How do I correct that income?

You can go back into your return and edit it. You may need to select to "add a state" just to get you back in. However, you say part year resident and I find many people don't look all the way through the form. They see a full year of income and decide it is wrong without looking farther down to find the percentage of income used against the tax liability on the full year of income.