The Siren Board

This is something that has been bugging me for a while now. I understand the overall concept of a Fedelcode siren, regarding the use of a damper plate to cut off airflow to the chopper, but I am still unsure of how the whole setup actually works, especially with the model 2. I have scoured the internet for hours on end, but was only able to find a couple of pictures, which didn't really help me wrap my mind around it. Any pictures, manuals, links, or explanations would be greatly appreciated.

I don't know if you saw this already, but here is a photo I found in Google Images:

The larger sirens like the Model 5 used a flat damper over the intake which, depending on the year, was lifted by a small motor or a large solenoid.