Lightning Cable Not Charging

[ask100]

I have two or three Lightning charging cables which gradually have all stopped charging my Iphone. The tips which were gold have gone a bit black.
Does any member know what can be done to get them to work again?
Please don't say buy a replacement!

[Tuvok]

Try cleaning them (power off obviously!)

For both my ipads I had long Belkin cables, which have gradually played up. Occasionally cleaning them, both ends, with cd cleaner, worked, but I subsequently bough a new one for my ipad4

[SparklyKid]

99p at home bargains, buy a few at that price.

[Maydup]

Rub them very gentle with an eraser. It should clean the carbon deposits and leave them good as new.

If not try a little WD 40 on a cotton bud.

[ask100]

Thank you all for your helpful suggestions.