This kind of corrosion should be fairly easy to remove. I have a set of small utility brushes, toothbrush size. one plastic, one steel wire, one brass wire. the plastic probably won't do much. The steel shouldn't be used on anything. The Brass one, is very soft, and scratches almost nothing, yet is quite good at stirring up corrosion like this, then using a softer bristle (like a standard paint brush) to remove as much as you can.
I would recommend due to the location, you should disassemble as much of this system as you can, checking the area above this connector. Looks like moisture has dripped down from above, and you should inspect every area you can possibly get to.
The alcohol is great also, I use 99%, but that's not easy to find.