Ariston A1535UK overfilling

If you get overfilling on an Ariston A1535UK look at the black pipe that goes from drum to pressure switch. Mine touched the case and wore through depite the foam rings to stop it doing this.

The symptoms may include rapid on/off on the fill valves as the air leaks away through the worn pipe. New pipe best, but if not available coat the worn bit with rubbery glue like Evostick and reverse it end to end so it wears in a new place. Mine wore through twice.