I have changed the rear brakes on this car (drum.

When putting on the new rear brake shoes, there is a small bar (horizonally) across the top that holds the shoes to the wheel cyclinder with two springs. There is a small catch on it that keeps the shoes to gether until you have put the brake drum on. When you step on the brakes it should expand the brakes to release the catch, but it is not doing this. I would think that the car would have to be running in order for the power booster to apply pressure to release this catch. Maybe the power booster is leaking and not enough pressure to actually expand the brakes?