You can screw in the needle adjusting sleeve (#33) as far as you like as long as the trigger (finger lever) remains free. It compresses the spring and applies tension to the trigger. It has to be screwed in far enough to allow the needle lock nut to tighten all the way. If you can't move the lever (#7) then it's too tight (screwed in beyond the end of the chromed body) or the rocker assembly (#28) has become unseated against the lever and jammed.
The tip (#3) should just come out. It just sits inside the ab body and the aircap body is what holds in place and seals it in place. It should just come out freely or with just a wee bit of wigglin.