I would suggest carefull removing the extractor and detail cleaning absolutely every crevice around every bit of it. And since removing the extractor takes a little bit of work and time, I would also replace the extractor spring while in there. It is a small coil spring and Wolff sells them, they are inexpensive.
To do this, remove the slide and tap downward from the top of the slide to remove pin. IMPORTANT! This hole in the top of the slide is merely an access hole that allows you to tap the pin downward. The pin itself is larger in diameter than this hole, this keeps the pin from ever walking upward and out of this hole.*
Replacement is the reverse -- pin is installed from underneath and tapped upward in to place. Important to tap the pin to below flush-- otherwise the pin could score the top of the alloy frame, you don't want that.
*ahhh, the joys of the dreaded "previous owner", who apparently figured that S&W bored the access hole too small... he enlarged it when he should NOT have and predictably, the pin wants to walk upward until it leaves the pistol on it's own. Bubba strikes again, but I still love the pistol.