That would be nice if everything was cut and dry. But it isn't. I have repaired thousands of things in the past 30 years from TV's to Arcade games, to the pro audio equipment and intelligent lighting. And the auto-self destructing nature of the Molex connector is constant and the major factor was temperature environment. The contacts themselves de-rate, heat up and burn plastic and is probably from the cheap metal they are using.I don't think that's derating with temperature. Switches or contacts should have close to zero resistance or they will heat up. The heating up is a function of the contact failing rather than the other way round. IMHO the contacts have either lost their springyness & are no longer tight or they have corroded. Either way there has been resistance introduced & that combined with a high current is what causes the heat. P=(IxI)/R.