Both vernier scales were not properly zeroed. After spending some time with a feeler gauge set and a known-good caliper, I was able to loosen the small Phillips-head screws and adjust each scale to zero. There is enough existing slop in the holes to allow the scales to be shifted to zero. The metric vernier scale was installed at a slight angle and I was not able to correct it. One of the tension adjusting set-screws on the top was not installed flush. I removed the screw and found a nub at the end that was not removed when it was parted, and the person that assembled the unit damaged the head trying to screw it in further. I replaced it with a screw from a caliper that I was throwing out.I expected problems like these at this price point and after adjustment, it works well enough for my application.