The instructions for a B&D 1/4" (price was right) replacement on how to replace chuck:
1. Unplug drill before changing chuck.
2: Open chuck as far as possible.
3: Check to see if a retaining screw is inside chuck. If so, remove screw in a clockwise direction (left-hand thread).
4: If no retaining screw, insert key into chuck and rap key sharply in a counter-clockwise direction.
5: When chuck loosens, unscrew it. Screw on new chuck.
6: Open chuck as far as possible and replace screw.
7: Chuck must be securly attached to drill.
8: Remove key from chuck before operating drill.
9: Make sure that drill bits or other attachments are securly locked into chuck by tightening all three pilot holes.
That worked for me. There was no screw, and I had to rap a couple times before it loosened. Too bad that wasn't the drill that needed a new chuck, but now I have a 3/8 chuck to put on the one that does (Sears Craftsman ca. 1976) if I can get that one off. The B&D? It's got other problems: only runs backwards.
Tom Gloger
November 2007