My front door is original to my home and has matching side lights. The house is eligible for the California registry of Historical Landmarks so I really need to repair, not replace the door. I noticed the crack at the beginning of winter and now I can see light through it. How do I go about repairing something like this? I can attach pictures if needed. The door was built in 1912 or so, I'm assuming when the house built. I also need to replace some glass in the side lights but I think I saw some articles earlier on that.