Hvac mode actuator went bad?

Hello, the mode actuator that controls the air coming out of the vents from the face to the floor went bad, and I purchased a used one from A-premium. It didn’t work and so I purchased a brand new one (same brand) and it didn’t work either. Well, I say it didn’t work, but when you turn the vehicle on, it Moves from one side to the other, and then stops, but when I use the controls on the center dash to move it from the face to the floor or to the defrost, It does not move at all. I have the automatic (HVAC) climate control in this Buick. So, I’m just trying to figure out what the issue is. Can you pull up the diagram and schematics of how to properly install it? Also, when working on this, I am going up under the dash on the driver side with my hand and long arms to work on this, because I would really like to not have to take the entire dash apart.