There are a variety of Black & Decker drills available on the market. The most common type of drills are cordless. The most common part needing repair on a cordless drill is the chuck, which is an adjustable grip mechanism for different size bits. When the "teeth" that hold the drill bits inside the chuck get worn down, it is necessary to replace the chuck.
Extend the chuck jaws fully. Insert the screwdriver into the bottom of the chuck.
Turn the screwdriver clockwise and remove the screw. This is known as a left-handed screw.
Tighten the chuck with the short end of a Hex Allen wrench. The Hex Allen wrench should be 1/4-inch or larger.
Strike the long end of the wrench against the chuck. This will loosen the chuck so it can be removed by hand. The chuck may not remove easily, and several attempts may be needed before the chuck will come out. The motor of the drill will not stop moving.
Remove the chuck from the drill and replace with a new chuck. That part and others can often be found on the manufacturer's website.
If the chuck cannot be removed, find a local service centre that can help.
Remove the battery pack before taking the chuck out.