I would say that the piston is cocked in the caliper, take the clamp off and remove the rubber dust boot, try and rotate the piston, this may re locate it and hopeful it will re seat, otherwise the piston will have to be removed and cleaned up, you will need rubber grease or brake fluid to lubricate any parts, do not use spray or engine oil.
Mark
Saturday, June 5th, 2010 AT 7:53 PM