Hello Hturner!
Welcome to The Canon Forums, and thank you for your inquiry!
We appreciate your participation, however we need to let you know that the Canon Forum is hosted and moderated within the United States by Canon USA. The PIXMA MG5765 is not a USA model. However. the technical support steps we would provide a USA model with a 5100 error code may still help. Since you have already checked the print head holder motion and made sure the ink tanks were installed properly we suggest trying the steps HERE. If your issue still persists and you live outside the United States, please go to http://www.canon.com, and select your country or region for additional assistance.
We hope this information was helpful!