My driver's side interior door latch manual lock selector cannot be unlocked from inside the vehicle. You can press it but it seems like it won't go far enough to unlock. The key unlocks it fine from the outside. Can I remove the hex screw in the middle of the door latch to get inside and fix it, or do I need to remove the whole inner door panel? I was afraid if I just removed the hex screw I might mess up a spring or something and then have more trouble figuring out how it works!