As far as the little thing that keeps tension on your needle valve.....

In a pinch, you can use a piece of fuel tubing to keep your needle set. (I say in a pinch....) I've been using a piece a fuel tubing on one of my beloved 46FX engines for a couple of years in place of the little black piece. All you have to do is take the needle valve off and shove a piece of fuel tubing about 3/4" long completely over the threads that the needle valve screws into. You then screw the needle valve into the carb body going through the tubing. You'll want the tubing to almost come to the end the needle. When done correctly, You'll actually be twisting on tubing if your needle needs adjusting.