[Radio Wrangler]

New chucks aren't terribly expensive, and it's not fun fighting with worn chocks and chuck keys. Chucks wear out faster than good drills, so really good tool shops usually keep a range in stock.

That drive dog may be in rather tightly. You'll need to put grips on it and likely use a sharp tap with a light hammer to free it. It's a normal right-hand thread.

B&D normally fitted Davies 'Multicraft' chucks. Some were OK, some cheaper models were too soft. Rohm chucks I've found are much better.

David