I think the other posters have covered most of the things that might be said ...
The typical probable causes of failures-to-extract in S&W 3rd gen's are a damaged extractor (chipped/broken), a damaged or weakened extractor spring; and a damaged or worn recoil spring.
Trying a new factory recoil spring is the easiest and quickest thing to try.
The extractor typically has to be fitted (filed and checked with a Go/No-Go gauge).
The extractor spring can vary, depending on the particular slide. There are a few different springs available for an armorer/tech/gunsmith to use in order to get any particular gun's extractor tension to fall within the recommended range. That can vary depending on a couple of things, one of which is whether the breech face is the older machined style (rounded shoulders for case base) or the straight (vertical) cut. Also, the way the spring well was machined can have an effect on this, and older 59XX guns might require a different spring depending on whether the hole was drilled by equipment operated by hand, or by computer. Guess which offered more potential for variance?
The tension is checked by use of a light weight force dial gauge, using a special attachment to hold the extractor hook and looking for the force required to cause deflection of the extractor tail (with the slide in a vise).
Of course, the final "check" occurs out on the firing line, after the bench checks are completed. Too much tension and you can get feeding problems. Too little and you get failures-to-extract (when the extractor spring is overcome by the recoil forces during what's sometimes called "moment of mass", and the recoil bounces the extractor hook up & over the case rim ... instead of remaining on the rim).
The lifetime warranty wasn't offered for private buyers until after it had been in place for a while for LE buyers of 3rd gen guns. The warranty is technically only for the original purchaser, or, for purchasers of demo/T&E guns that were sold used, but with a factory warranty offered. Sometimes the company doesn't ask ... and sometimes they do. It's
their call whether they choose to ignore or invoke their stated warranty policy.
Doesn't hurt to ask, though.
Naturally, the ammunition being used (and its own potential tolerance issues) and the cleanliness of the chamber ... or even a "tight" chamber among an older 59XX barrel ... can also have an influence on "sticky" extraction.
Also, the older barrels marked "9mm Parabellum, in small font, instead of the more recent "9MM stamping", in larger numeric/alpha stamping, had some minor changes to their chambers. The 5906TSW barrels with the newer barrel hood markings supposedly had a slight change in their inside chamber wall angles, if I remember right, straightening them by something like 1 degree.
I've seen what happened when someone tried to remove an extractor pin in the wrong direction, using the wrong tools. It permanently ruined the slide. Extractor replacement isn't something I'd ever recommend be attempted by someone who does have the knowledge, tools and some actual experience.
Sure, you can always find someone, somewhere to managed to remove one of the tightly pressed solid extractor pins (in the right direction, using the right couple of pin punches), and who happened to use just the right extractor spring for
their particular 59XX gun. Depending on luck isn't the best of plans for diagnosing and repairing a firearm, though. Nor the safest.
Once an extractor and/or extractor spring is requires replacement in an older 59XX, I typically like to also replace the ejector. The older ones had short tips and a sharp corner angle under the rear of the tip that could sometimes develop a stress riser. The revised ejectors had longer tips for faster ejection (especially with hotter duty ammunition) and a curved angle to help prevent a stress riser from occurring. The ejector works just as hard as the extractor, working in combination each time the gun is fired, you know. It's a drop-in part (presuming knowledge of frame disassembly), as long as the right one is used, of course.
Try calling the factory, or seeing if there's a local gunsmith familiar with S&W pistols. The extractor & spring are pretty inexpensive (something like $20 for the extractor & a buck for whichever spring is appropriate). It's the labor that costs (and any shipping).
After all is said and done, it's not a difficult thing to check and correct/repair for an armorer, tech or gunsmith familiar with S&W pistols. Once it's done it's probably good for many more years and more rounds than you might be able to afford to shoot through it.
Just my thoughts.
