3/8 Drill Driver, chuck replacement. - Craftsman 19.2V C3 DRILL/DRIVER

SOURCE: Dewalt Drill DC728. Chuck came out of drill body

If you find that the end of the screw inside the chuck is actually broke then you have a gear problem inside your drill. This is actually a very common problem. Sometimes people push too hard on their drills and the gears inside wear out and break. This prevent the motor from wearing out, but, the gears have to be replaced.
If it is the gears and not the chuck. you broke the minimium of the front gear or gears inside your drill. YOU CANNNOT repair gears. they need to be replaced. you may be able to find some off brand gears to work but, you run the risk that they are not as strong as your original ones, or may not be exactly grooved correctly.
so, if replacing your chuck does not work. find replacement gears. IF you cannot find the gears from the manufacturer see about replacing your drill.
If the chuck is still good, keep it. If you buy the same model, keep your old drill for replacement parts, ie, switch, armature, cord, etc.
hope this helps somewhat.

SOURCE: Dewalt XRP Drill Chuck will not come off

you need a special jig to remove the chuck on this kind of drill

SOURCE: porter cable 884 cordless drill

Most chucks have a tolerance the cordless drills where designed for drill bits 1/8 and larger the 3/8 chucks are a little better with the smaller bits .Check your owners manual and see if they have a min requirement listed for the bit size

SOURCE: relace keyless chuck

It really depends on the model. Here is a general description of how to remove most regular keyed and keyless chucks from corded and cordless drills:
Some chucks have a Left Handed screw that secures them to the spindle so they do not come loose. You can look into the chuck with a flashlight and see if there is a chuck screw. (It may be a torx head, flat head, or philips head) You will need to remove this screw first before doing anything else. Sometimes there is loc-tite applied to the screw so it may be stubborn and sometimes you will strip the screw head. Remeber that the old saying lefty-loosey, righty-tighty does not apply here. Left is actually tightening a left hand thread, so you want to turn it right to loosen. I know, it will feel weird but thats the way to loosen it. You may have to apply some heat to the screw in order to get that loc-tite to break. A pencil torch works great. If you strip the head out you will have to use a drill press and drill the screw head off.
After removing the screw you can remove the chuck.
To remove the chuck, the easiest way is to use a hex socket bit and an impact wrench. Put the hex bit in the chuck, and depending on the condition of the jaws, tighten the jaws as much as possible to the hex bit. Put the impact in reverse and bump it until the chuck is loosened. If you do not have access to an impact wrench you will need to put a hex key with a long arm into the chuck and tighten it then place the drill on the edge of your bench and give it a good whack with a 3lb hammer. It may not come off immediately so you may have to reset and do this a couple of times. Not the most effective way to remove a chuck, especially if one of the jaws is missing, but that is what most manufacturers tell you to do. I myself cut the collar off with a die grinder and then use a pipe wrench on the body of the chuck applying constant pressure while heating the chuck body with a torch. Works every time. Heat is our friend on stubborn chucks. Good luck, any questions please post.