One common thing that occurs…if the machine gets a little too hot, it will pause and the yellow light will come on until it cools down. The Basic and Plus models need to be run with an ambient temperature of from 60° to 75°F. If you have one of those models and the room is a little too warm, it might pause the print to cool itself off, and the higher the room temperature, the longer that pause is going to last. (Keeps you from burning out the tube prematurely.)
You can try pointing a fan at the air intake on the lower right side of the machine (underneath) but if you open the lid, it will kill the print, so try the fan first.