[fredjacksonsan]

If they're corroded, they probably have some white acid buildup on them.

To remove, make a wet paste of baking soda and water. Apply carefully or with something you can throw away later. Let it bubble awhile, add a little water, then rinse with more water. Repeat until it doesn't bubble. You might want to consider replacing the cables if they're badly corroded, as this method might not get all the acid that's within the strands of the cable.