OK, so this may be somewhat stupid, but I'm a bit puzzled. I'm a beginner mechanic and I've done some work but nothing with wheels.
My wheels were fine, brake pads are fairly new (Kool-Stop Salmons) and braking was fine. Then, last week, I had a flat tire. I fixed it at work but on the ride back home I noticed a dragging sound. One brake pad was dragging on the front rim. At home, I readjusted the front wheel until it looked right and didn't drag when I spun the wheel with my hand. I didn't give a second thought to it. I didn't ride for a few days (travelling) but when I rode in to work this morning the dragging sound was back! Sure enough, the wheel was dragging on the same pad.
After fiddling with the wheel it seems that no matter what I do I can't get the rim to center between the brake pads. There's no wobble, it just always leans on the same pad. Since the pads are fairly new and haven't worn down yet, the barrel adjuster is all the way in, leaving the largest space between the pads and the rims. The only thing that actually seems to move the pads far enough away is the little brake release lever but if I release that, braking is very poor.
Bike is an '07 Specialized Allez. Alexrims S500 rims.