So I just purchased a 2005 SID World Cup with carbon steerer. I have the top of the steerer EXACTLY flush with the top of my stem and then an additional 10 mm spacer. I thread the cap into the plug (or bung for you overseas-ers), which is supposedly specially made for carbon, and begin tightening the stack. I have tried this several times, and each time the plug, instead of expanding and staying put, moves up and out. I tried to increase the pressure on the steerer, and thus the plug, by tightening the bolts on the stem (slightly) first, but I'm not sure this is allowing adequate pressure on the stack because I can still detect faint movement. Any thoughts, help?