Re: source 4 575 vs 750
Usually the screw that is in the burner assembly covers the hole for the extra pin on a 77V HPL lamp used for dimmer doubling. This existed on both older, non-750 fixtures and newer fixtures. The third pin on a 77V lamp is on the opposite side of the lamp than the pin on the HPL750, so removing the screw probably won't do you much good.
If you upgrade your fixture with the retrofit kit and a new burn base, you shouldn't void anything on the fixture. If you are upgrading older fixtures to accept an HPL750, chances are it is out of any warranty it had.
Now, if you are drilling holes in the burner assembly, you might be negating the UL listing of the fixture. Whether this is a good idea or not is up to you, however I know plenty of end users who have made this simple modification. As the third pin on the HPL750 is purely there for alignment and designation, it carries no electrical current. Modifying the burner assembly, if done carefully and precisely, won't alter the electrical properties of the fixture, and should not render the fixture dangerous. If one were going to make this modification, one would probably want to dissemble the burner assembly before drilling.
Usually the screw that is in the burner assembly covers the hole for the extra pin on a 77V HPL lamp used for dimmer doubling. This existed on both older, non-750 fixtures and newer fixtures. The third pin on a 77V lamp is on the opposite side of the lamp than the pin on the HPL750, so removing the screw probably won't do you much good.
If you upgrade your fixture with the retrofit kit and a new burn base, you shouldn't void anything on the fixture. If you are upgrading older fixtures to accept an HPL750, chances are it is out of any warranty it had.
Now, if you are drilling holes in the burner assembly, you might be negating the UL listing of the fixture. Whether this is a good idea or not is up to you, however I know plenty of end users who have made this simple modification. As the third pin on the HPL750 is purely there for alignment and designation, it carries no electrical current. Modifying the burner assembly, if done carefully and precisely, won't alter the electrical properties of the fixture, and should not render the fixture dangerous. If one were going to make this modification, one would probably want to dissemble the burner assembly before drilling.