i had a simular problem with my prime.
Please check if there is any material in the tube from the head to the pump.
There should be an transparent tube going from the Back of the Head all the way down in the back of the machine.
Its between the support and Material tube.
You can unscrew it to check.
If there is ametrial in it please come Back and post again.
I will show you how to change the tube (normaly it hardens inside the tube) and to setup your Pump again.
This problem comes from not switching off your machine while waittimes over 48 hours.
If the material arrives your pump it will be defect! I managed to clean it out and get it to work again. But thats a lot of work and hard to do.
Attached is a picture of the vacuum tube.
In this shouldn´t be any material!