The water level in the boiler is maintained by using a number of different components. The water level probe also called the auto-fill probe, is the most simple component of the system: a stainless steel rod which penetrates the boiler and contacts the surface of the water inside the boiler. Though very simple, it is often the cause of most autofill problems. A lack of continuity on the level probe will give a false reading and lead to fill issues. Removing the level probe, checking for continuity, and correcting the continuity issue (if there is one) will rectify many problems. We carry replacement water fill probes for La Marzocco, Simonelli, Astoria, and more commercial espresso coffee machine brands. Explore our collection.