I bought a Bezerra Ellisse with a fault described as “lots of steam escaping”, so the first task was to take the end cover off the boiler and replace the gasket. This is also a great time to have a look inside.
Disconnect the power. Turn off the water supply.
The boiler can be drained using the tap under the drip tray. Mine was blocked, so I recommend taking a bolt out of the end plate (behind the copper tube in photo below) and siphoning out any remaining water (later edit: it has a blanking plug over the tap outlet – only remove when the boiler is cold).
Make a drawing of the wiring from the pressure switch to the element, and then disconnect the wiring and the pipework at the boiler end and lift the pressure switch clear.
The mains filter may be in the way, so loosen the two allen screws so it can be moved clear if required. The controller backplate also needs to be removed and the controller tied out of the way (not shown).
Remove the earth from the boiler end plate.
Loosen the nuts a little at a time to avoid distorting the plate (17mm socket). You can see here the element has already been removed (together with two of its studs).
With the end plate off, the heat-exchanger pipe can be seen running diagonally. The vertical tube is a baffle around the level probes. There is very little scale in the boiler and the element looks new in the photos below.
The old gasket was brittle and cracked, and is most likely the cause of the steam leak.
Remove all the old gasket material using a scraper and finish with a brass brush.
Place the new gasket in place.
Replace the end plate and tighten the nuts a little at a time, tightening nuts cross-wise to avoid distortion.
Next to be installed is the heater element gasket. This is first slipped on to the element, which is carefully guided into the boiler, before rotating so that the element rests in the lowest part of the boiler.
With the element in place, the wiring connections can be remade.
Re-tighten all the fixing bolts.
Insert the overheat thermostat vial, which slides in about 200mm or so.
Here is the side view of the completed installation.