Start with WD40 to clear out the crud, possibly taking the handle apart for cleaning, then use 3-in-1 oil for lubrication.

Using just WD-40 will get them back to the same problem once it evaporates.

I love wd40, but it’s more a cleaner than a lubricant. It will dry up unlike actual lubricants.

WD40 is a degreaser. Which cleaning out the old lubricant is how it helps.

After you need to spray in fresh clean graphite lubricant for these sorts of mechanical movements.