My 1993 C2500 has a door unlock issue. My power door locks are working correctly, powering the actuator both ways when power is applied. The power door lock sucessfully locks the door, but fails to unlock the door. I can unlock the door ONLY by using the ket from the outside. In using the key and looking down the window chanel , the lock/unlock cam on the door latch just does not slide over enough to get that last bit of pull needed to unlock. When I turn the key, I can see the rod bow just enough to unlock the door. This is pretty frusturating now, and I question if the door latch may have a problem, as everything was working just fine prior??