In the summer months, the screen door is all that separates you from would-be intruders including insects, stray pets and marauding scavengers, such as raccoons. A door that does not close all the way provides a gap for insects and a purchase for enterprising animals attracted to your cat’s uneaten dinner. Fixing such a door is not rocket science, and in most cases can fix it with just a screwdriver. More often than not, the problem relates to the door's hardware, including the hinges and the automatic door closer.
Tighten all the screws holding the hinges with a screwdriver. In many cases, this is all you need to do, but you may find that some of the screws no longer bite. You can fix that with epoxy wood filler.
Unscrew the hinges and take down the door, then remove the hinges from the door. Mix enough epoxy wood filler with hardener to fill the holes for screws that you cannot tighten. Trowel the putty into the holes with a putty knife and wait for it to set.
Drill a pilot hole in each hole you filled with putty, using a drill and a 1/8-inch bit. Attach the hinges to the door, then support the door on a block of wood while you screw the hinges to the door frame.
Adjust the automatic door opener by screwing the adjustment bolt on the end in or out with a screwdriver. Some closers have two bolts -- one for adjusting the swing speed and one for adjusting closure. Tightening the swing speed bolt increases tension, and tightening the closure bolt makes the door swing more quickly and close more firmly.
Take the door off the frame, lay it on a flat surface and plane the edges with a hand plane if the hinges are properly adjusted, but the door stays jar. This is usually a sign that moisture and humidity have swelled the wood. After planing, touch up the edge with paint or varnish.
Adjust the alignment of an aluminum screen door by tightening the screws in the four corners of the door with a screwdriver. These screws can loosen, and when they do, the door falls out of square and does not fit in the frame. The screws are easy to access when you take down the door and lay it on a table.