Worked at a computer company (in a past life) and asked this materials engineer (whose specialty was connectors) what to use. He recommended contact cleaner. In extreme cases (green connectors) he said a little rubbing with an eraser might work. (Followed by more contact cleaner)
He also recommended dipping the connectors in baby oil after treatment to keep oxygen from them.
In a pinch, I have been known to use brake cleaner instead of contact cleaner and toothpaste for a mild abrasive.
The absolute best fix was swapping out that ugly wiring harness for the pristine one from the parts car. I sure don't want to do that again.
So....... if corn oil is made from corn and peanut oil is made from peanuts, what is baby oil made from?????
Ken