At least six very noticable
scrapes. I was sure that as soon as I turned the switch back on, the
bulb would burn out with a bright flash. I flipped the switch, and
the bulb worked as a normal bulb......

This all happened a week ago. I've used that trouble light with that
same bulb several times. I've moved it, banged it, and turned it on
and off many times. I can tell the filament is loose because whenever
I move the cord even the slightest, the movement of the filament is
visible. I have been carrying around a new bulb, but I dont plan to
install it until this bulb really does burn out. I simply can not
believe that a bulb that burned out with a bright flash TWICE, and
shows all the scratch marks on the glass from a dangling filament, is
still working and apparently healed itself. I have never seen
anything like this...

As has been said by another poster, there are better options for
trouble lights... low voltage models and even fluourescent models.

But, if you like the old fashioned ones with the incandescent bulb in
a metal cage, you might want to consider using what are called "Rough
Service lamps". These have thicker filaments and are less
susceptible to damage from vibration.

Beachcomber