i just changed my karni (e1) the other day! see the pin above the trigger? its what the trigger swings back and forth on. you'll need to take that out. crazydriver84 explained the steps to remove your frame. you'll need to do this to get to that pin. there will be a screw (very small) as you look 'down' into the top of the frame holding that pin in place. loosen the screw till you can push the pin out. take out the old, drop in the new. put it all back!

heres a youtube link that shows you how, as my directions are probably terrible...
http://www.youtube.com/watch?v=weIdVC6F5HI