Hi DIYerJ. Welcome to the forum. This is typically what happens when one of the parking brake cables is stuck partially applied. The clue is the frames of the shoes must contact the anchor pin on top AND there must be a little free play in the parking brake strut rod. If either of those are not true, the parking brake strut will hold the shoes out a little.
If a stuck parking brake cable is the cause, you might be able to get it to retract by flexing the outer casing or by using a pry bar to force back the lever the cable is attached to.
Tuesday, September 14th, 2010 AT 10:23 PM