Anyone used an RCBS old fashioned scale?

I have a brand new 5-0-5 but it seems to give me different measurements on the exact same amount of powder. If I simply move the counterweights around and then move them back into place, it has the tendency to be off a grain or so, although it is usually less than that. I often tap the end after I center it to see if it will return. Sometimes it does, but then if I tap it again, it will be a little bit off. I'm a beginner and I am working on the lightest load possible, but I would hate to be loading too hot because of the scale. Once I charged a few rounds without seating the bullet to make sure they were about the same, and while close, there were some slight differences in the amount of powder. What I am wondering is should I get a digital scale and ditch the old school teeter totter style?