Marantz 1060 fuse

hello,
several months ago i acquired a Marantz 1060 amp. After cleaning the switches out with contact cleaner it has performed flawlessly for me since i've gotten it.
however, some previous owner had cut the power cord down to about six inches and installed a rather sketchy-looking plug on the end of it. so i finally decided to replace the cord. I simply unsoldered the old cord inside the amplifier, and soldered a new one in it's place. when i plugged it in, all was well. but when i turned the power switch on, the fuse blew. i rechecked all my connections and everything seemed fine, so i tried another fuse, and that too blew immediately.
the fuse specified on the back of the amp, and the fuse that both had been in there originally and the one i replaced it with were 250V 2.5A fuses. the fuse is wired on the incoming AC, before it goes to the transformer (i've attached this portion of the amp's schematic- it is too large to post in it's entirety).
so i took out my multimeter, and checked the incoming AC, and found it to be 120V, and around 5A.
so out of curiousity i attached a 250V 5A circuit breaker i had lying around in lieu of the fuse, and sure enough, the amp powered right up. but the transformer became very, very hot (since no doubt it is not supposed to be getting more than 2.5A).
what i do not understand is why this fuse had not been blowing out before, nor what i can/should do to correct it. any help would be much appreicated. thanks.
 

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Seems like the amp might have decided that now was the time to self-destruct. Pull the outputs and test them (and see if you can power up with the outputs removed without using a much-too-large fuse...a dim-bulb tester here is a great idea, as you're putting that transformer and very likely a lot of other parts in jeopardy).
 
at what point do you suggest i pull the outputs? disconnect after the bridge and smoothing caps? straight off the transformer secondaries? after the pre-amp, but before the transistors?
i'm still unsure how- with 5+ amps coming in from the wall- the fuse wasn't constantly blowing in the first place.