You need to press in the actuator fingers to turn it back if putting a new disk in on an old PP. Then again if you bought a new PP it should be turned to that location already. Its how you set them back, did you understand what they were doing in the link?
Make sure springs are compressed, and make sure you can't see the plastic tabs through the vents. SAC mechanisms are USUALLY fine out-of-the-box, but if the box is dropped or something in transit, they can arrive out of adjustment.