manual door lock not popping up all the way when cold.
 

Okay, I've been going through the forums and haven't found anything pertaining to the issue I have. I have manual door locks and now that it's winter I noticed the door lock won't pop up all the way to the point where I need to turn the key in the lock and hold it while I open the door. I've also noticed that when the sun is hitting the door it unlocks normally but the door lock peg (for lack of a better term) still only comes up less than half an inch as opposed to the passenger door peg which comes up almost an inch. How can I fix this?