Open the door and inspect the hinges. Tighten the hinge's screws if they are loose to bring the door back into place. Remove the middle screw of the hinge if it will not tighten. Drive in a 3-inch screw to affix the hinge to the jamb.
Draw the jamb into the framing underneath by drilling in a 3-inch screw at the sticking point.
Place a piece of masking tape on the edge of the door closest to the jamb, running a piece all the way up the door. Close the door. Place a compass against the jamb with the pencil resting toward the door's edge. Bring the pencil and compass together and run them down the door along the tape to make an 1/8-inch line.
Remove the door from the frame by taking out screws from the hinges and take the door down.
Turn on a belt sander and run it along the side of the door that was taped. Run the belt sander up to the line but not through it to remove wood that is causing the door to stick. Occasionally stop sanding and place a carpenter's square against the door to make sure you are keeping the sanding flush. Seal the edge of the door with a similar stain and rehang it.