Corner edges of aluminum siding, the end caps, get banged into a lot. You cut a corner too sharply and knock into them with ladders, the lawn mower, garden hose, bikes, you name it. End caps are very easy to replace. All you need are replacements, aluminum nails, a pry bar, a utility knife, silicone glue — preferably clear — and paint to match the siding.
Follow these steps:
Take off the damaged caps.
With a pry bar or pliers, remove all the nails underneath.
A screwdriver or cat’s-paw can also slip under the heads, lifting them enough to grab with pliers or a claw hammer.
Starting at the bottom and working your way up the corner, slip a replacement cap under the bottom edges of the panels above it.
Nail the cap down.
Put the next cap on, repeating Steps 3 and 4.
Do it until all but the last end cap are fastened in place.
Cut the nail strip off the last end cap with the utility knife.
Spread the silicone glue on the back of the cap.
Slide it in as you did the others.
Press down so the adhesive grips the wall.