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See if your model of range finder has a setting for 'close', 'short', 'distant', 'medium', etc. Some do, though the better ones don't, such as the Nikon 550, automatically shift from one range to another.
How old is your Nikon rangefinder? has it ever been dropped or otherwise mishandled? Has it gotten wet, at any time?
Try removing the battery from it, leave it that way overnight, then try it again.
It's good to hear that you sensibly took good care of the rangefinder.
I would advise trying the 'rest reset', with the battery out and the rangefinder completely unpowered, for at least 4 to 8 hours or overnight. It might loosen up the distance-range/mode selection.