Completely remove the power cable.

You will clean it using a homemade chemical solution composed of vinegar and salt. The same solution used to clean old coins.

On a mall cup of tea add vinegar until it almost fill up and add a small tea spoon of salt and mix it up until the salt dissolve.

Drop the contained metallic part inside the solution and wait for about 10 minutes.

Remove it and check if the corrosion was removed. If not repeat the process for more 10 minutes. Dot not forget the metal inside the solution for a time longer than10 minutes or the solution will star to corrode the metal and make things worse.

Finish it by cleaning it with a tooth brush and alcohol isopropyl.

Before clean.

After clean