I have pointed out what it is that I think I must push to release the lens(#1) but the part which moves when I to (#2) doesn't clear what I think may be holding it back. I can retract the rails and attach the hinged flap to line up (or so I think) but it doesn't move.
Maybe it is just old and hasn't been opened in years.
I took this photo with Skitch and perhaps you might need a better shot taken with my camera?