Are you certain the clearance light even worked prior to this "inspection"?
Puzzling that the guts of the fixture disappeared. Generally the guts are riveted to a plastic tab in the base of these lamps. Even if you had a time dated photo of all the lamps burning (making this thread moot), finger pointing probably will not go far.
I would locate and purchase a replacement fixture exactly the same, or of similar design, and mounting style. A couple butt splices and crimper, silicone caulk.
Perhaps depending on the original install "I'd" contemplate retrofitting all of them with LED replacements. This would possibly avoid having to monkey with conventional filament bulbs ever again.
Preface: you're using a safe adequate ladder.
Remove the defective fixture gaining full access to original opening. Discard.
I would start with (circuit not energized). Equipped with a small flashlight and a compact mirror.
Using a slender piece of reasonably stiff bare wire (length of which is determined by distance to next lamp) with a small L or hook on the end. Probe the cavity gently for the wiring harness. Depending on this lamps relative position, sweep towards the rest of the lamps. If your lucky, you'll snag the pigtail socket that you can replace with your new lamp.
Depending on how this step went would determine a possible step B.
Best of luck.
J & J
+ Kickr's the Vonderhund
, ES-38RSSA, 19.6K#
, 3500HD-Max, CC, 8'-DRW, 9.1K#