If you can't get a secure wrench on the rubber hose side and you are committed to replacing it... Cut the rubber hose so you can put a 6 point socket on there. Flare wrench on the steel line side did not work well for me, it would not budge. For some reason it came loose really easy with a pair of channel locks. If the fitting gets mangled you will need to cut the old flare off, replace the fitting and flare the line.
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