Sounds like the sear spring might not be doing what it's supposed to. I too have noticed that in the notes there is no "lost the first pull" situation directly addressed. And while I can't from your description give you a clear instruction on how to fix it, I can suggest that you do like I did and remove the barrelled action from the forend, and then screw the trigger guard to it with the crush collar in place. Then put the bolt in and check function of the trigger, if you have a similar pull to when the rifle is assembled, you'll be able to see how the trigger, sear and striker are ineracting and this will give you a very good idea of which areas need adjustment (adjustment to be done when the rifle is reassembled).
If when you pull the barrelled action and assemble it with the trigger guard the trigger pull is nothing like the assembled rifle you could pack the trigger guard a bit here and there to try to set up the trigger pull situation you have with the rifle assembled.
This means of making it visual has helped me with a number of rifles and for me it helped get a far better grip on the mass of information in the articles to which you have been referring.