1. Level is when all points are normal to the direction of gravity across its length.

A level surface (plane) is one which is normal to the direction of gravity at all points in its length

https://www.studocu.com/en/document/university-of-johannesburg/surveying-3b21/lecture-notes/surveying-3b-chapter-4-introduction-to-vertical-distance-measurement-leveling/3878251/view

2. Therefore, when a surface is not level, not all points are normal to the direction of gravity at all points in its length.

3. When all points are not normal to the direction of gravity, the points experience differing degrees of gravitational pull because the normal force is always equal between gravity and the points in an object when the points in the object are normal to the direction of gravity.

In a simple case such as an object resting upon a table, the normal force on the object is equal but in opposite direction to the gravitational force

https://en.wikipedia.org/wiki/Normal_force

4. Therefore, when you adjust a spirit level from unlevel to level, you are adjusting it from not normal to the direction of gravity to normal to the direction of gravity and from all points not being under the same gravitational pull to all points being under the same gravitational pull.

Now if UA is analogous to gravity, we should be able to just substitute the “gravity” for “UA”. This is what we get.

1. Level is when all points are normal to the direction of UA force across its length.

2. Therefore, when a surface is not level, not all points are normal to the direction of UA force at all points in its length.

3. When all points are not normal to the direction of the force of UA, the points experience differing degrees of UA force because the normal force is always equal between the UA force and the points in an object when the points in the object are normal to the direction of the UA force.

4. Therefore, when you adjust a spirit level from unlevel to level, you are adjusting it from not normal to the direction of UA force to normal to the direction of UA force and from all points not being under the same UA force to all points being under the same UA force..

Which of those points is incorrect?