Measure top and bottom of damaged section.

When replacing a corner bead, you must measure at least 1.5 inches from the corner.

Use a straight edge between the the top and bottom and draw a straight-line connecting the marking.

You can even use the putty knife if the damaged section is not too long.

Mark with a pencil, or cut lightly with utility knife.

Use caution when using the utility knife as the blade is very sharp and may cause an injury.