This is a cross-post with the C&V forum, because I'm basically a C&V guy--don't do much with modern bikes.
My wife's hybrid has a small amount of play in the headset. I went to tighten it in what I think is the usual way: loosen the pinch bolts, then tighten the cap bolt enough to get rid of the play. Didn't work: the cap nut turns freely, but is evidently stripped--where it threads into the star nut, I'm guessing. The solution should be to remove the cap bolt and cap, drive the old star nut further into the steerer (not a carbon steerer or frame), and thread in a new cap bolt.
The problem is that the damn cap bolt won't come out. It turns freely, but I can't think of a clean way to get a strong enough grip on it to remove it. I tried all the easy obvious stuff, like pulling up on the (loosened) stem while turning the bolt, gently prying up on the cap with a screwdriver, etc.
This can't be an uncommon problem. Any ideas? Sacrifice the cap bolt by drilling a bunch of holes around the bolt head? A dremel or rotozip-type tool would make that easier, but I don't have one.
As an aside, I'm kind of confused as to how this bolt stripped in the first place. I had it out a year or so ago to install a stem extension so V. could ride the bike after some shoulder surgery; after she healed I took off the extension and reinstalled the stem directly on the steerer, adjusting it correctly at the time--I know I didn't overtighten it. What gives?