The air control mechanism is a plate that slides in a track. This plate is connected to a control rod with a spring handle that allows you to move the plate between the fully closed and fully open position. This mechanism controls the primary air that is delivered to the stove for its different burn rates.
The rod should slide smoothly and you will feel a small a mount of light friction.
The rod should make a metallic "tunking" sound at both ends of the sliding action.
To check the stroke: measure the spring handle when it is open and then when it is closed. The difference will be the stroke. On a K-180 or a K-181 series, the control rod will have about 5.5" of stroke between the fully open and the fully closed positions:
You can watch this video to visualize how the mechanism slides: https://youtube.com/shorts/q_qnjog97FY
Please note that this video may not be for your exact stove, there are different strokes for different models.