liquid electric tape this stuff is pretty amazing.

This may be a stupid question, but why couldn't you slit the rubber grommet entering the battery compartment so you don't have to remove the securing nut? I understand the grommet is there for waterproofing, but a razor cut shouldn't compromise integrity that much if at all. If you're really paranoid you could use a bit of liquid electrical tape to make everything watertight afterwards.

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And thank you again for this writeup. Great stuff.