My wife, Jenny, used to yell at me… well, chide me, in that VOICE, that wives have, about this little trick I know, that saves doors and doorknobs, and tempers, that about 80% of the time, works with only 10 minutes of your time. It is a miracle trick. Kids! DO try this at home!
We would be going to some teacher function at somebody’s house, or a party, and Ding Dong! Oh! Jenny and Sam! Come in! And we would, and the homeowner would either wrestle with the door to close it, or haul off and slam the crap out of it. 
Sam: Wow! How long have you been having to slam your door like that?
Jenny: Saaam.
Homeowner: Oh, two years.  (I have had people say 6 months, and a year. One woman said “Since I bought this dump.”)
Sam: Holy crap! I mean, wow, that’s a long time. Let me look at this for a second.
Jenny: (the VOICE) Saaaam.
Sam: It’s ok honey. This will just take a minute. You go ahead on in.
I would pay for that later. So, most doors that have that problem, also have issues with making the deadbolt work, or the door to latch closed as well. The culprit in most of this, is gravity.  Gravity is the net acceleration that is imparted to objects due to the combined effects of gravitation and centrifugal force. The speed of that acceleration, the speed of gravity, which seems to be the way they measure it, is 9.80 m/s2.
I am sure that somewhere, Jenny is saying, “Saaaaaam.’
So, for two years, gravity has been pulling down on this door at 9.80 m/s2 of potential acceleration every second of the day. And one side of it is screwed with hinges, to the stiff house structure, and can’t move very much, but the latch side of the door can and does. Either the door becomes a slight parallelogram, or the top of the hinge side doorjamb pulls out of line. Both resulting in the top corner of the latch side of the door to bang on the jamb, or it sags on to the threshold making it drag or bind up.
The remedy for this, is to open the door, and remove the screw on the top hinge that is highest on the hinge and closest to the center of the jamb. It is most of the time, a short 1″ screw. Then you take a 3″ deck screw, (which, of course, I always have a box of in the back of my truck. Such useful things, 3″ deck screws.) and drive it into the screw hole you just opened, and hope it is long enough to catch the stud that frames the opening. Then you tighten the deck screw down until it is contacting the hinge surface. Then you give your screwgun trigger one final tweak, to really seat the screw. Most times that is all it takes.
I was in Tulsa Oklahoma this past week, doing some minor fixups to my buddy John”s house, and he took me around to various small bars in the evenings where we listened to the most delightful bands. Yesterday I drove across to Oklahoma City, to visit my big sister Bunny. I love visiting her. I feel safe there, and we always have lots to talk about. So, when I first came in, I noticed that her front door was dragging on the threshold, and she had to wrestle it a little to get it closed. And the deadbolt wouldn’t engage the jamb, leaving only the wimpy knob button to secure the door. Not good.
Saaaaaaaam.
Well, heck, what was I supposed to do? I woke up this morning with a mission. I came downstairs, and looked around the corner, and said, Bunny, I’m gonna fix your door. Then walked away from her protestations, because, well, I’m Sam, that’s how I roll. I can’t let a good front door be damaged when I can fix it. And I am autonomous enough to get away with it. So I did the screw trick, and it didn’t help.  The screw just bottomed out but wasn’t moving beyond that. 
But I have a lot of tricks up my sleeve. I didn’t give up. I needed a miracle here. A properly installed door would have a shim between the door jamb and the stud framing the opening. I so rarely see a properly installed door, and because of that, my little trick almost always works. So I had to get rid of the shim so the jamb would move. That meant carefully taking off the interior door trim piece on the hinge side of the door frame. With patience, you can cut the caulk on the sides of the casing trim, and carefully pry off the piece, so that you can put it back on when you are done. Just to insure that I would not break the trim, I did a laying on of hands, and put the healing energy into the wood. I heard something behind me, and saw my sister’s husband standing there looking curiously at me. 
Sam: Just fixin your door here.
I got the trim off whole. Behind it was a proper cedar shim right behind the top hinge. I took my deck screw out, and used a painter’s tool to split the shim into pieces and pulled them out of the space. I drove the deck screw back in until it touched the hinge, gave it a tweak on the screwgun trigger, and closed the door. Better, but not perfect. I gave the deck screw another tweak. It closed smoothly and with almost no pressure. And flick! The deadbolt engaged with only some slight pressure pushing the door up against the weatherstrip. Which is how a door should work. I have installed at least a hundred doors. They all work like that when I am done. I reshimmed behind the hinge, took the nails out of the trim piece, nailed it back on, and it looked like it did before I started. Except the door closed easily. It closed so nicely that I felt like Jesus must have felt when he worked a miracle. I almost had an epiphany.
Carried away on my wave of success, I stepped outside, and had a look at the storm door, which wasn’t closing very well either. Same issue. Gravity. And a broken top hinge. A couple screws and a hole drilled and screwed below the break on the hinge, and voila! Another miracle! I stepped out into the yard, and threw my arms open, looking up at the overcast sky, and sent my thanks up to the baby Jesus, and a beam of heavenly light from on high came right down upon me and bathed me in its golden glory. And I smiled at the universe. Well, ok, it was just a stray sunbeam breaking through the clouds for a moment, and not some heavenly beam, but just the same, it felt good. I love my job.
You’re welcome.