I see thanks for the info. Now I will give you my first solution, in case this is not fix the issue do not give negative rating (it will only destroy my over all rating and will not helpful on both of us). Just reply and I will do my best to help you.
Based on your given information it possibly have airlock in the pump and water intake system
Try to manually prime your machine, for instruction CLICK HERE it supports all gaggia and seaco models.
Sometimes you need to get rough on your machine in able to remove the clog air on water line. slamming the water tank into machine sometimes help. If still, unplug your machine, remove water and turn the machine upside down or shake your machine if possible.
Let me know if you still have questions.
Hope this information will be helpful.
IMPORTANT: If you are satisfied to my answer please don't forget to rate,,GOOD OR EXCELLENT rating and BONUS are greatly appreciated...