POTS:
You're doing it right - the starter should be a short punch, but needs to be a little smaller than the hole (

) and long enough to clear the top of the slide. Still a bear, I'm told....
(I'm going from Randy's video - I've not tried it yet. Yet....)
I would try some Kroil, just for the heck of it. I don't think that S&W uses Loctite, and it shouldn't need heat. (If you want to try heat, keep it real cool

.)
Check Randy's video if you can find it - I can't find the URL right now. "Randy Lee" and "Apex" and "Extractor" would be the keywords I'd try first.
(That's the ONLY thing I miss from a PPS40 I had. The extractor was held in by a sort of push-button thing. Nothing to it at all.... Unfortunately, it required a course in magic to put it back

.... Well, almost.... You really had to be careful.)
Regards,