[pjsg]

MY first job (in the last 70s) was working in a TV rental store doing small item repair. In particular, repairing toasters was probably my #1 activity. Essentially the failure was nearly always the same -- one of the three toasting elements failed, and so I would replace all three elements, and the customer got a working toaster back.

It was never clear to me (at least I don't recall it being clear) why the heating elements failed. It could be from someone sticking a hard tool into the toaster when trying to remove a small item (and breaking the element). It might be that a piece of bread gets stuck to a portion of the element and catches fire at that point -- maybe that weakens the element at that point. This was, of course, long before toasters got electronics in them!

[toast0]

The heating elements in a toaster are essentially the same as the heating elements in a lightbulb. Eventually, enough heat cycling, the metal fatigues or melts at a certain point, the circuit opens, and your toaster stops lighting up the room. Of course, trauma is always an option too.