Or, it could need some sort of repair. The manual you can download at Coats does cover calibration, at least.
The difficulty in balancers is two-fold: Measuring the force, and then calculating how much weight to put on to cancel that force out. The calculation depends totally on the geometry. There are 3 inputs to the geometry. If that part is wrong, you might think you can zero one out given enough time, but it's not easy, at least not in dynamic mode.
I haven't seen a manual to deal with when it's truly broken. I know they have some error codes, but I've never seen much discussion online about really fixing one.