Car power lock doesn't work all the time?

I have a 2000 Ford Mustang. My power locks works to lock the car but not to unlock them. I push the button on the drivers side and it makes a noise and tries to move but doesn't. Any suggestions?

Do the power locks work good with the key FOB? If so, the switch is what'is going bad, or the connection is bad at the switch.

Door lock actuator sounds like it is faulty (probably part of the whole latch assembly) (don't really get that age mustang over here but ford falcons of similar age are all intergrated) but for the falcon's the main problem is a snapped shaft in there, which you can buy separate, and rebuild your current actuator

Hi simple the locks and locking mechanism are all worn and need replacing.