I'm would hope that this problem has been resolved by now, but I thought I would throw in a few pennies for current and future readers.

Along with what has already been described, I have seen the glue that holds the coil in the brake loosen after extreme temps, causing this same problem. Very difficult to diagnose, since most brakes are cooled down by the time a tech arives, or maint allows them time to cool, so they can work without being burned. NOTE: This time lapse allows the coil to settle back into place, since the brake is mechanically applied. Hence, allowing the brake to appear as normal.