I ran into an interesting problem on my 1994 Fadal 4020. I was machining blocks to a height of 6.000 . When I check it with a height gauge it was small by almost .005 I thought it may be a faulty reading on the height gauge, but the height gauge is correct. X and Y axis check out, so this is unique to Z axis only. I thought it may be a backlash problem, but that is correct also. I checked the axis card for calibration and it appears to be set right as well. Would a bad resolver cause this? The machine doesn't give me an error.