The only thing that should be going through that little 1-2mm passage is the skinny end of the accelerator pump plunger. Looking at the carb sitting upright, the spring would be underneath the fat end of the plunger. The length of the spring isn't real critical. After you put it together, open the throttle and watch as the plastic arm pushes down on the pump. If the plunger doesn't return all the way back up, just pull the bowl back off and stretch the spring out half an inch or so.

 

So the spring actually sits on the end of the plunger rod and on the float bowls. not touching the brass spacer, correct?

 

i don't have the time right now, but if you want, i can find you a picture of the spring where it belongs for you later tonight

 

Should I just go ahead and fork out $25 for the assembly?

 

There are lots of different ink pens out there now a days, the springs are all a bit different, the old style, screw apart in the middle type is what you want, the spring is about 3 times stiffer than the stocker, so it works a lot better, look for a spring that is about 1" long, and about 1/8 " in diameter, it should drop right in, and it will work for years, and if you find a pen, it's free !!!