Hi Black-cat,
Welcome back to the HP Support Forums! :) I see you are running into some print quality issues on your HP Deskjet 2540, you have also noticed a decline in printing. I appreciate your troubleshooting efforts and would like you to continue here: Fixing Ink Streaks, Faded Prints, and Other Common Print Quality Problems
I understand you may have done some of the steps listed in the troubleshooting document, I would like you to complete ALL steps in order to resolve the issue you are experiencing.
As for the decline in printing, can you please clarify and let me know what you mean? Are the printouts slower than usual, or do you mean the quality in prints? I would like to make sure the print quality is fixed before continuing with another issue. Please let me know the following:
1. How are you connected, wireless or USB?
2. What is your current Operating system?
I will watch for your reply.
Thank you,