That bolt-looking thing is a diode. It prevents voltage from the whirling fans (which become generators after the ignition is off) from keeping the engine running.
That spade terminal is really not intended to connect to the terminal on the top. While you have it out, can you solder a small pigtail with a male spade terminal on it to mate to the black wire?
It seems to me if you had a bad connection there - your fans would not come on.
Rocky
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