Fender Super Reverb tube guitar amp loud buzz hot power transformer What caused this failure?

I have seen this failure on other amps in the past. Evidence of a overheated power transformer, internal failure. Of course the best course of action is to install a new power transformer, which will be the case here. Normally, I would just replace & move on, but I wanted to show this failure and see if anyone out there may know the cause. 1. Is it simply a breakdown of the transformer over time. 2. Was there a Filament short causing excess current that eventually opened the CT? 3. Since it was from Sarasota, FL was the salty air a contributor, generated corrosion which attacked the wiring? It would be interesting to know the exact cause of this breakdown. I have a replacement transformer in route, so this one will be replaced. So, chime in, let me know your thoughts!