To replace my trigger bar I had to venture where few dare go--to disassemble the frame on my PM 9. First, there is a great archived AR15.com article here: http://www.ar15.com/archive/topic.html?b=5&f=35&t=102618

Second, to answer a couple questions raised in the archived column:

If you have a pin versus Torx screw, use a small, flat blade screwdriver to VERY gently pry underneath the side plate near the pin. It is friction fit and mine lifted out easily about 1/32" inch at which point I eased out with mini needle nose. GENTLY!

To reinstall the trigger....insert the trigger bar first, ensuring it is behind the pawl on the sear and install the side plate (yes, you install the spring as in the photos!). Slide the trigger only in the bottom of the trigger slot and fiddle the tab of the trigger bar into the upper right hole on the trigger. Then carefully ease the trigger pin on from the right (trigger bar) side to engage the right flange of the trigger--don't let it protrude into the "well" where the spring goes.

Then insert the spring and spacer as a unit--straight leg of spring to the left, bearing against frame. This is the tricky part--you have to ease the spring spacer around so the flat portion bears against the matching portion inside the trigger well--keeping enough tension on it so that the spring is aligned--and then use small needlenose to press the spring/spacer into place. I used a small pin to capture the left flange of the spring and once I had that in, I was able to get the trigger aligned against the spring pressure and feed the actual trigger pin through.

In short, install trigger bar, slide trigger in from bottom, insert pin partially on right side; insert spacer/spring and wiggle into place; align and press pin all the way in.

Lastly, it looks like the new Torx screw can replace the old pin directly--but it is a TINY screw and don't have the rights torx driver yet....

Good luck!

PS--if you get a new trigger bar, note where the spring slides against it and make sure it is dead smooth--use a very fine stone to clean it up if need be. Mine was rough and caused a bit of a gritty trigger pull.

I just went through this.
There is only one way the trigger spring and spacer can go in and work correctly. The first few times you try it can be very frustrating.
But once you get how to do it, it's not bad.
The above instructions are correct. But until you do it, it's very hard to picture.

Dave N