Lightning cord 4th pin went black

So I’ve had my charger for about 5 months, and after a few uses I noticed that my the 4th gold pin on my charger went black. At first I thought nothing of it as my phone was charging fine but now my phone doesn’t charge or a message will pop up saying “accessory not supported”. I’ve searched up remedies to what they say is corrosion that I could try to remove the blackness from the pin but none of them work? Is there any other ways I can try to remove the corrosion in my charger?