1/4" fiber sticks do it every time...they're flexible enough to get around corners while stiff enough to push through insulation. Fish tapes can go off track and arch over. I hardly ever use mine. But if the string's already there and not hung up, just tape another follow-up string to the cable and pull it through so you wind up with cable and new string in place. What I hate is firestops in the wall cavities. They're headache enough with no insulation, but when you have to contend with firestops and insulation, man...that's lousy. Anyone got a solution to getting past bracing in the middle of METAL frames? I can step-drill through metal top plates OK, but what do you use when you hit a brace half way down inside? Is there a long drill extension that fits a stepped bit?