Well, not too long after I posted that and emailed him, I got a phone call from Gene Malkoff. After a few minutes, Gene had me up and running. Evidently, there are some differences in the Stingers over the years, and Gene is working on straightening these issues out. My particular problem was that the polarity was reversed on the pins & bulb socket. I had to back that screw out to prevent it from touching the brass base of the drop in, then flip it around and install the drop in backwards. Worked like a charm! All I need to do now is trim that screw down so I can screw it in flush without the possibility of it touching the drop in's brass base. If that happens, it will likely short out my battery or fry the flashlight.
The MDSTG is very bright, a huge improvement over the original bulb! Some of my standard tests are illuminating a street sign two blocks away from my house. It easily passed this test. I can light up the inside of a car by shining it through the tinted windows very well. The spot is fairly large, with lots of spill. It lights up a large room or a yard pretty well. I use my lights in the field, I am not a white wall hunter, but I did find that the spot was free of holes and has few subtle rings. Certainly much better than many LED lights I have paid much more money for.
All in all, this was a great investment for me, well worth the money. Gene's customer service and business ethic continues to impress me. We spent more than 20 minutes chatting on the phone, even discussing some of his current and upcoming projects.
If you've got an old Stinger on the shelf, I would highly recommend the Malkoff MDSTG.
--Frank