As I'm not quite sure if I fully understand the problem, please correct me if I'm off-target on anything written below. Under typical operating conditions, it is perfectly normal for the steam pressure gauge on a machine of this design to rise and fall in a regular pattern. This occurs as a direct result of the boiler being heated up to the point where the steam pressure flips the pressurestat off (which operates like a thermostat in a sense for the water in the boiler) and then cooling back down to the point where the steam pressure drops low enough to switch the pressurestat on again. The speed at which this occurs will vary from one machine to another. Additionally, heat exchanger machines heat their brewing circuit's water by pulling heat from the water that is steaming--As the machine pushes cool or cold water through the boiler to be heated, it will see a drop in temperature and a matched drop in steam pressure, to the point where the machine may start re-heating the boiler (and rebuilding pressure). Basically, It's nothing to worry about under normal circumstances! I hope this helps.