given that this device is apparently dumb and useless, IS there a good device for leveling a table, other than just slow rolling balls around from corner to corner? I mean, is there something that will tell you EXACTLY what's wrong? e.g. lower left needs to go down X, upper right should come up Y, tweak upper left a little also, the slate is humpbacked and should be tossed, etc?
Locally we have been having trouble with one particular table, it seems like as soon as you fix one corner or area, another area gets wrong, and now we're at the point where balls roll in the opposite direction as if the slate was arched a tiny bit in the middle. I've heard this is possible, but I'd love to have a surefire way to confirm if this is the case here or if our testing just sucks.