To put the cable into the carb slide, you have to have the open end of the e-clip (attached to the needle) as well as the open end of the retaining c-clip (sits on top of the other clip) open to the slot in the slide. Make sense? Probably not. Here's a picture from Norm's section. http://motorbicycling.com/attachment...arbpict004.jpg
and the link to the thread if needed http://motorbicycling.com/f39/motori...build-302.html
On your original question. Yes you need to compress the spring to get it together. Once the slide is assembled, makes sure the slot on the slide is aligned with the pin in the carb. The slide will go together the wrong way but not work properly. Assemble with the carb off of the bike and then look through the intake or the air filter (filter off) to see the slide move and return when you work the throttle.