Found this information as a guide while searching on "firing pin plunger". Hope it might help.
Insert extractor into slide. Install the firing pin and use the punch to push the firing pin in far enough to clear the firing pin stop cutout. Install the firing pin stop and release the firing pin.
•For Series 80 only: Insert extractor into slide and align plunger cutout with hole. Turn slide right side up and insert plunger and spring. This will help keep the plunger spring from falling out or kinking up in the slide. Push the extractor into place to lock the plunger into the slide. With the slide upside down, depress the plunger and install the firing pin. Push the firing pin in far enough to clear the firing pin stop cutout and release the plunger. It will hold the firing pin forward. Install the firing pin stop and press the plunger to release the firing pin.
http://www.10-8performance.com/id9.html
Edit: One other thought comes to mind... you probably already did this, but compare the stock extractor with your other extractors side-by-side and look for differences that might cause what you are describing. If you want to take some pics and post them up we can help look them over, too. I understand that the Ed Brown part is not a drop in and needs to be fitted. I don't know about the EGW. I have read that the Wilson Combat extractor is a drop in part that may only need the tension adjusted, so you might look at buying one of those if you have to.