So you have an older quality Jacobs chuck that has problems — maybe it’s stuck and could use a good cleaning, or perhaps the problems are more severe from a lifetime of spinning bits in the jaws and you need to replace parts. How the heck do you do it?
Jacobs has a short guide up on their website but we found two (#1, #2) other sites that detail how to disassembe and reassemble the standard Jacobs chuck. Once you get it apart you can inspect for damage. You’ll have to buy a repair kit that consists of new jaws, split nut and if it’s a ball bearing chuck, new balls and race. Oddly, Jacobs doesn’t have those up on their site but they are available from any industrial supply place such as MSC or McMaster Carr, even on Amazon [What’s This?]. It’s worth checking eBay for them from time to time as well if you rebuild machine tools as a hobby or business.
Often just a good cleaning and lube job will make the difference between a chuck that works well and one that has you swearing like a sailor.