To remove the first stage:
silver solder a 4-40 nut on the front of the trigger, towards the top so the screw that goes thru it hits the bottom of the receiver and will push the trigger back, taking up the slack
Make sure to put a small coil spring between the head of the screw and the nut, just like on a carbeurator, to prevent backing out
Sounds like you done good already
Shootingly
John