My machine sat on the shelf for over 5 years. I tried the priming suggestion and couldn’t get ANY water to flow into the pump. I tried compressed air also with no luck. I suspected a blockage in the pump itself so I took it apart. I found that one of the one way valves was stuck shut from calcium deposits. Once I freed the valve it worked like new. If you attempt this make sure you keep track of all of the o rings and small parts and the order of assembly. Also make sure that the machine is NOT PLUGGED IN TO AN OUTLET as all of the electrical parts are exposed.