Brakes' combination valve stem is out, how do I get it back in?

I've got an '87 Caprice. I replaced the master cylinder and bench bled before I installed it. I also disconnected all lines and electrical at the combination valve because I needed to pull it to repaint my frame where all the brake fluid had leaked from my old master cylinder. After hooking up all the lines again I bled the brakes, rear-right, rear-left, front-right, front-left and my brake lights are staying on. I noticed the stem on my combination valve seems to be out and I read in the service manual it needs to be pushed in to "reset" the combination valve. How do I do this? I tried just pushing it in but no luck. Don't want to force it unless maybe that's what I need to do? Thanks!

Yay for the iPhone's shi**y camera:
http://i121.photobucket.com/albums/o...o/43de3358.jpg

2 People,key on engine off, one person in car pushing brake pedal and watching light, second person opens bleeder on front caliper, as pedal goes down and when light goes off immediatley stop the brake pedal and close the bleeder. may take several attempts and if the light does not go off you will need to repeat the process at the rear brakes. What your doing is using fluid pressure to center the valve. Also this is assuming that the brakes have been properly bled.