i have a 94 mustang convertible and when i try and unlock the door with the button, the drivers door wont unlock. the passenger door unlocks normally. they both lock normally as well. i have to use the key to unlock the drivers door. when you press the button, you can see the door lock pin move slightly but it doesn't move enough to unlock the door. any ideas on what this could be? thanks

 

Bad actuator. My Powerstroke does the same thing with both doors but my actuators are part of the latch mechanism and I have been too cheap to replace them. I think you are lucky though and yours is a seperate piece.