Originally Posted by SD Blue

Beware of using abrasives for cleaning. Too coarse and you can induce other problems. Some of the best "abrasive" cleaners I've used: Pencil eraser, Ink eraser for more stubborn corrosion and Mr. Clean Magic eraser.

The "specialty" contact cleaners are less stressful to the plastics used in connectors. For female connectors, the sprays are very handy and usually take care of the problem. Isopropyl Alcohol and even brake cleaner can be used but can cause the plastic to become brittle, which is more of a factor in 25yr. old connectors.

About the only time you need an abrasive of any kind is when there is corrosion to the point of sluffing of metal and pitting. Many contacts have a very thin plating of more conductive metal or "tinning" and abrasives wear this away very quickly.