Electrical problem
2000 Ford Explorer 6 cyl Four Wheel Drive Automatic 137000 miles

Hi just recently my front passenger door lock has started to act up. It will unlock just fine but when you try to lock it whether by panel buttons, remote, or outside keyless entry the only way to lock it is to physically push it down and that gets harder every time. Also my rear passenger door lock is the opposite at the rare time its unlocked it will lock fine but it gets harder to unlock each time. At first you could just pull up on the knob while pressing the button now only once in a blue moon it will unlock on the first attempt or after pressing it over and over and over again. What could i do to fix this annoying problem