WD-40 is not good for this. find some watch or instrument oil, and you'll be much happier. use the tiniest amount you can apply. over oiling just attracts dust and causes wear down the line. look at watch oilers online, they're not particularly complicated, but they do allow very precise and small amounts of lubricant to go where you need it. Naptha (ronsonol) is what my grandparents always used to clean clocks and watches, coleman fuel should be the same stuff. just make sure whatever you use doesn't have alcohol in it, or you will dissolve the shellac holding the rubies/bearings in place! Dial indicator isn't much different from watches and clocks in principle.