Membrane regulator with reinforced silicone hose. Membrane regulator is a frequently replaced item in all Jura espresso machines. If leaking profusely, it could leak water over electric transformer and may damage it as well.
Replacing the membrane regulator does NOT always fix the SYSTEM FILL error. There are many parts that could cause SYSTEM FILL error. It could be the Multi-way valve, Pump, Dispensing Valve's or the Thermoblock. Isolate the cause of SYSTEM FILL to the component before ordering the part.