toasters lepesach

Question

Recently, a reputable kashrus publication stated that toasters are tested by the manufacturers by actually toasting a slice of bread - those who requre libun gamur have claimed that as a result - even a new toaster cannot be used for pesach - since libun gamur is not possible. Is this in fact the metzius? If so can one rely on hesek mibachutz - i.e. simply raising it to its highest temp for some amount of time - If so does this constitute libum chamur (because it is mateches) or simply libun kal to be relied upon (for chametz) in cases of great need? Looking forward to a reply kt zc