I had the same symptoms and, like you, took it apart until I could go no further. Then read your post and took heart. Put it back together and everything worked perfect again. My guess; the clutch indexing splines jumped a cog or some such thing. When I had mine apart, I slipped the adjustment collar over the clutch and rotated it fully to/against the drill stop setting. Then made sure the adjustment collar drill stop setting symbol was positioned at the top of the tool when I put it together again. ... Working great for now.

One thing that sometimes works is to try to "tighted " the chuck onto the shaft a little. Sometimes the chuck backs off a bit and puts alot of pressure onto to screw, by trying to tighten the chuck down a bit first it will release some of the pressure on the screw. Since yuor chuck is jammed try this.... Put the drill into "low" gear( #1) then make sure the clutch setting is all the way into drill mode. Clamp the chuck assembly itself into a large vise with the drill body sticking straight up and try turning clockwise very sharply and hard (trying to tighten the chuck down ). Remove the drill and try again to remove the screw ( which on the dewalt is a torx size t-20 and left hand thred (clockwise to remove). Once the screw is out try the same method to remove the chuck. Clamp the chuck tightly into a vise and give it a hard sharp snapcounter clockwise to remove. ..... Good luck and let us know how you made out

I'd like to take this opportunity to share one of my experience and method of taking it off ( which actually works) looking at the photo of the cross sectional view of the chuck as seen in an earlier thread. I first measure 1" from the back of the chuck and I make a mark,then I take an old/new hacksaw blade and I make a mark on the chuck outside.and thats where I take an angle grinder and I cut the front of the chuck off so that I can access the back end of it,and then I hit the rest off using a small cold chisel in the same direction as if I was unscrewing it. The whole process usually takes me about 15-20 mins to complete,but it worked

Well, I had to wait a while to get a couple of 2" #20 Torx tips to give it one last try and both "bit" the dust in vain. I then started cutting away the body of the chuck ( as was suggested by gdea) exposing the three jaws. By cutting all three jaws through to the round( I don't know what to call it) I found that whatever had jammed the chuck had been released!!! Probably one of the jaws had become misaligned and prevented the chuck from screwing.( A terrible thing indeed!!) Anyway, I wanted to thank those of you who responded and relate what turned out to be a fairly easy fix to my problem- at least when I finally tried it.. (Or was I just lucky-I don't know!)

First off an allen wrench will not remove the torx head screw, and you may even strip the head of the screw trying to remove it.

[B]Dewalt DW953 drill chuck screws use the T20 Torx head screw[/B], and the body uses the T15 Torx head screws. I use the Craftsman Torx head screw driver set, which has all the common sizes.

[B]The T20 Torx head screw is left hand threaded, which means you will have to unscrew it by turning the screw to the right (clockwise)[/B]. Most traditional screws are right hand threaded and are tightened turning them to the right (clockwise).

Try the torx tip screw driver before attempting any other method.

If for some reason the head is stripped you can drill the head of the screw off only. Requires several sharp bits lubed with small amount of oil and slow drill speed, starting with an 1/8" bit or smaller for your pilot hole, then use a 3/16" drill bit to remove the head only. You can now use the allen wrench method to remove the chuck ( http://forums.ereplacementparts.com/power-tool-repair/8-removing-cordless-drill-chuck.html ).

got the screw off by using a endmill then all I had to do is remove rest of screw after chuck was off

I haven't heard of anyone using that method before. I'm glad it worked out!

I tried drilling first but that inner screw is hard, all I did was burn up good drill bit, cheap 5/16 endmill bit in a drill press took head of screw off real easy,

Mike has a great post on this. Under how to remove a cordless drill chuck.

Paste this into the search this thread at the top of the screen and it will take you to the post Dale is referring to

Removing a Cordless Drill Chuck

Hi Brokenbit. That gear selector switch on top of your Dewalt DW953 is mechanical, not electrical, so it's possible that replacing it will not fix your problem. It seems more likely that you have an issue with the gearbox, specifically with the switch's mechanical connection to the gearbox. If the previous owner had the drill apart, he/she may not have reattached the selector switch properly. You might want to check that.

I picked up a Jacob's brand chuck from Home Depot today for $25. Pretty good deal I thought, but i'd still like to hear what ya'll think about other chuck upgrades out there. I'm not very stoked on this particular one because of it's weight (call me a sissy, but it's way too heavy!)

There are [I]tons[/I] of replacement chucks out there, and many of them are Jacobs brand. It's always a trade off between durability and weight. Lots of people really prefer an all-steel chuck because they last a long time and they don't wear away if you're drilling against other material. Plastic chucks tend to be lighter but the plastic sleeve can break or eventually wear away. They're also usually cheaper. :)

Did you manage to put a 1/2" chuck on your drill Scottathon?

I did end up with a 1/2" chuck. So far im loving it too.

!'ve got another question about the same drill; While in the midst of replacing the chuck I also to the liberty to take about the drill and clean out a bunch of hair/dust inside of it. I used some automotive grease inside the gear box (it was the only grease I had lying around) and it now makes a very high pitched whine when running.

Could the grease have damaged it in some way? It still works fine as a drill, but makes this terrible noise now. :confused:

Sorry it took me a while to get back to you. I don't think the new grease is the problem. If the drill is making a whining noise you've probably put something together wrong. Maybe something in the gearbox is aligned wrong, or maybe the motor isn't seated properly. You might want to take the drill apart again and see if something needs to be realigned.

Roger that. I'll try getting it apart soon and let you know.

No worries on the late response Mike. I'm greatful theres a forum like this that exists with knowledgable people like yourself on it!

Hey doyle,
As far as I know the fiber gears are not available in steel..the gearbox has to be replaced as a whole unit..part # 380264-06 avail at ereplacementparts.com..
the gears are functional as a engineering torque transferring mechanism designed to have a less load operating capability on the dc battery power source..oh...and it costs less..:)
hope this has been helpful..?
cmoorejack