original bumper jack question

found an original bumper jack in the parts car so I took it out and started to jack the car up just a smidge to see if it worked (car is also on jack stands) but now I can't seem to get the jack to come down. How do you make the jack release? I flipped the little on/off switch but I can't get the jack to go down. I can always jack it up with a hydraulic jack and get it out but I'm curious how it works to get it down. Of course the sticker on the bottom of the trunk lid with the instructions is long gone in both my cars.
thanks,
-Tim

This brings back memories from my youth. I used to have a Ford that did the same thing.

After you get it out try putting some oil on the moveable parts. Work it up and down just like you would if you were jacking up the car. It should loosen up.