Off subject maybe for this *part* of the thread, but:

I carry a couple of Mini-maglites (AA) and one Solitaire (AAA),
and have for years.

Where I've *often* (well, regularly!) had bad-contact problems is:

1: Back at the tail, between the small end of the spring
and the minus-end of the rear (or only, for Solitaire) battery,
the fix that seems to work for me is (via my Leatherman, which
I also always carry on my belt (except on airplanes, Go* D**n
WMD lies, terror "colors", the admin pushing fear, fear, fear,
especially as an election nears -- I could go on!), 's) file --

a very gentle brush with it against the rear surface of the
battery and also *very* lightly on the small end of the spring,

2: As someone's already mentioned, between the big end of the spring
and the wall around it, via light brush with the file (on the
spring).


FYI: It's amazing how fast that file wears -- and all I do with it,
just about, is use it on maglites!

(When stupid file wears out, what do I do, buy another
$80 Leatherman "Wave"?)


David