Bubble leveling skill of level meter

Level bubble leveling skills are as follows:

When the bubble is facing a certain leg (that is, the line connecting the bubble and the center of the circle is approximately perpendicular to the bottom where the leg intersects with the pan/tilt), the other two legs remain motionless, and the leg is moved back and forth directly along the vertical projection line of the leg, and the leg is moved back and forth along the vertical projection line of the leg.

When the bubble is not facing any leg, adjust any leg (move back and forth along the vertical projection line of the leg or lift the leg), keep the other two legs still, so that the bubble is facing any leg, and then move back and forth or lift the leg along the vertical projection line of the leg.

When the bubble is on the circular line of the bubble in the circular level (just touch the line), turn the foot screw to center the bubble, and the bubble will be horizontal.