Shortly after the warranty period, the trouble begins

Were we at first enthusiastic about the device, we are now also equally disappointed by almost exactly two years.
The tanning result is now very uneven. The browning increases with each toasting: toasts to the second Toast on the same level (. For example "2"), they are dark brown, rather than lightly browned. A third passage (of course with new Toastbroten :)) delivers almost black Toast, as if they were toasted at the highest level.
Very strange only that the problem occurred shortly after the end of the warranty period ...