The small bulb was probably not turned all the way in its socket and eventually vibrated out. Small bulbs like that don't have the best finger grip and someone may not have pressed it in far enough to twist past the twist lock notch. Tape on a stick was a good idea. I'm not sure what I might have tried before also thinking of that. Maybe a little magnet taped to a string. Maybe a bit of putty on the end of something. Far simpler than removing the taillight to shake it out, probably the simplest solution if I was away from home and all I had in my tool kit was screwdrivers, pliers and wrenches.
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Dave -still with 940's, prev 740/240/140/120 You'd think I'd have learned by now