On/Off O top teflon oring install - what's the trick?

[Aegis]

Mag newbie here, but trying to learn. Took both mags apart after watching the video, no problems. The only grief is when I try to get the the top teflon o-ring in, using the on/off assembly to push. I seated the silicon o-ring, put the teflon o-ring on the pin and pushed the entire thing into the body.

It keeps popping out of the other o-ring that is already seated. Finally got them together, but it took waaaay too many tries. Any tips?

[BlackVCG]

Install the pin into the bottom piece with the groove pointed so that it will point down when the gun is pointed straight forward. Put on the on/off top piece and then install the teflon o-ring onto the top of the pin. With the other o-ring seated at the bottom of the valve, push in on it on/off assembly. If it pops back out a bit, that doesn't matter. As long as you can get the valve in the body it will be fine. Once it's gassed up, air pressure pushes down on the assembly and the mainbody holds it in place.