I use a stainless steel wire brush on the end of a long handle to scrub the element cover prior to bringing it to the boil. It works really well. Obviously I still get crap build up on it, and occasionally during a 90 minute boil it might cut out a bit towards the end which another quick scrub fixes. After the urn is emptied, a combination of an initial scrub with a plastic brush with some hot water, then boiling a bit of water and citric acid gets rid of it (this also removes that brown scaly **** with the aid of some steel wool). Thing comes up like new every time and no rust issues either.