I think the trick is to tie something lightweight to the end of the string that fills the tube; like a tissue or ping pong ball (larger conduit). You may also be able to use a fish tape to pull the string through.
I always have success with light string and a small piece of tissue paper. Just tie the string around the middle of a kleenex or a piece of toilet paper, then tear off the tissue until you have a small loose bundle that will fit into the smurf tube.
I push the loose end of the tissue with my finger first with the string tied end trailing it.
Another critical part: have somebody feeding in the string while you vacuum. I've found that the vacuum is strong enough to pull the string through, but it's not strong enough to pull the string off the roll or across the rug.
I was only pulling through about 50', however, so YMMV.
A forum community dedicated to home theater owners and enthusiasts. Come join the discussion about home audio/video, TVs, projectors, screens, receivers, speakers, projects, DIY’s, product reviews, accessories, classifieds, and more!