1997 Ford Aerostar passenger power lock not unlocking - sti

The power locks work when they are locking...but...when I unlock them all of them unlock except the front passengers side. You can hear that the lock is trying to go up but can't. If we keep pressing the unlock button about 20-30 times the lock will slowly rise. It's like there is something not getting a great connection or something inside the door lock is bad.

Please help, it's driving my wife crazy, which drives me crazy.