I have tried searching and researching all across the net and user manual, I'm getting nothing. 

I can't get the O2 to turn on in my P-47.  Before flight, I put on the mask, flip the switch to full O2 for the preflight check, and the blinker doesn't move, I have zero pressure in my tanks.  I thought it might be a gauge issue so I took her up to FL200 and passed out, so now I know I'm not getting O2.  Anyone know how to fill the tanks?

I figured it out      Thanks for the reply though (I had already asked them too, I was waiting for a response when I posted this thread)