My Raleigh Sports has been chugging along since last summer quite fine, but lately I've noticed some strange noises from the rear and upon further investigation learned that my rear wheel is out of alignment and by rear brakes are remaining closed around the rim after I disengage them. I'm brining the wheel in to get trued at a LBS, but I would like to fix this brake dilemma on my own. i tried loosening the horse-shoe-shaped clamp over the pads, but it's not making a difference.

Essentially, when I compress the brake handle then let go, the pads only come off the rim slightly, but still retain some friction. Any ideas to fix this?

Thanks!