How to adjust bubbles with optical theodolite

There is nothing wrong with the instrument. It's all small things. For the case that the third surface is not centered, it can be adjusted with a calibration needle. Turn the instrument to the third face and see how much it deviates. Use the pointer to adjust the screw next to the bubble, but only the bubble deviation 1/2 can be adjusted. After turning the instrument, center one or two surfaces with the anchor screws, and then turn to the third surface to see if it is centered. If it is not in the middle, repeat 1/2 until all three surfaces are in the middle.