Just for the continuity of this thread and, I suppose, for statistical purposes, the bottom heater element in our Elson Coral E would seem to have packed it in after some 5 years' service (it was itself a replacement element at the time). We are currently using the booster function (i.e. the top element, I believe) as a temporary, but expensive solution for our hot water until we can get someone 'round to fix it. The new replacement element should obviously be without the built-in thermal fuse which was found on older models and which had a tendency of blowing and causing a very severe leak in the process.
10, 2 RQ