Not Brewing. When I press the brew buttom water starts to travel to the K-Cup and then stops. I

Question

When I press the brew buttom water starts to travel to the K-Cup and then stops. I have to open and close the k-cup lid 4-5 times and press brew several times to get the water to start running throught the cup. It seems as if there is not enough pressure to push the water through the machine. The water reservior is full of water.