OfficeJet 7612 Printhead Not Filling Ink Tank Reservoirs

My OfficeJet 7612 wide format printer is not filling the ink tanks in the printhead. I have changed the printhead, ribbon cable. and purchased new cartridges. During the power-up diagnostics, I can hear a pump run twice for about 3-4 seconds, but no ink enters the 4 reservoirs. The rear rubber tubes don’t appear to be damaged and are connected to the printhead Everything else on the printer works.

What pulls the ink into the printhead ink tanks and how do I troubleshoot it? Any idea what could be wrong? Thanks