The pump is not working. How do I fix it?

First thing to check is that the pump is getting 24V from the power supply. LED 5 on the CPU is an indicator that there is 24V available

If you have the 24V and the pump is not seized then it is either a faulty pump or most likely a bad cable or connection in the wiring harness for the pump.

If you hear a buzzing sound from the pump it has power but it is blocked with ink. You can try to flush the pump out but normally its not that successful.