Print quality is an important factor for customer satisfaction. Resolving print quality issues poses special challenges for a manufacturer's support organization. The authors have developed a troubleshooting website to enable customers to self-solve many of their print quality issues. The diagnosis is based on images of printed test pages that contain highly accurate simulations of potential print quality defects. The authors review the process for developing the website, the organization of its content, a validation framework to efficiently verify its correctness, and the steps to simulate print quality issues. The tool has been deployed for more than a dozen color laser printers and used by hundreds of thousands of customers.