Regarding accuracy of the counterweight scales, it’s been years since I’ve worked in a place that uses them, but I recall that they were required to be officially calibrated regularly.
You would think that the fact that the indicator is hovering between the up and the down limits (with no weight on it) that that would mean it is accurate, but maybe not necessarily. I remember the calibration dude coming’ round with a set of special calibration weights.
mmm