The cache is not at the marked location, you must solve the puzzle to get the real coordinates 

Puzzle begins

Assume 40 and 84

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Minus

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plus

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minus

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minus

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minus

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plus

____________________________________________________

plus

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plus

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minus

You can validate your puzzle solution with certitude.

feel free to message me if you cant find the solution

if cords seem slightly off, after puzzle is solved Subtract N .003 Add W .003