Several folks have mentioned lubricating. Perhaps a good idea, but I'm not sure I'd use WD40. As popular as it is (I do use it in some applications) it is intended to be a water displacing substance (Hence WD), not a lubricant. Nor is it a penetrating oil, though in some applications it does seem to work that way. A light machine oil like 3&1 oil, reel lubricant or sewing machine oil might be a better choice if you're going to use oil.