Battery Terminal arcing

You found it already. The arcing connection needs to have the battery post and the cable clamp cleaned and tightened. Consider doing that to the negative cable too.

Be aware that standard procedure is to remove the negative cable first, then remove, clean, and tighten the positive cable, followed by cleaning and tightening the negative cable. The reason for doing it in the exact order is the negative cable connects right to the car's body and any metal parts. If you bump the wrench into any of those metal parts while it is in contact with the negative battery post, nothing will happen. Next, as long as the negative cable is disconnected from the battery, if you bump the wrench into a metal part while it is in contact with the positive cable, nothing will happen and you can do the service without worry.

The potential problem comes in if the wrench is on the positive battery cable, and it bumps into a metal part of the car while the negative cable is still connected. You will get really huge sparks, and it is possible for the wrench to weld itself in place, then become red hot and actually melt under its own weight. That can also lead to a battery explosion because batteries give off explosive hydrogen gas.

If you only repair the positive cable, just be careful that the wrench does not touch anything other than that cable clamp.