1977 Grahams Vintage Porto

[andrawes76]

I was having a super day today and decided to celebrate with some friends. I have bottle of 1977 Vintage Grahams Porto in a magnum and wanted to bust it open with some cigars. Checking out the bottle, looks as if its a leaker. Its not a wide-spread problem, just a singular incident and the bottle is still high shoulder, so it appears to be minor. Curious to know if the leaker, which obviously means oxygen in the bottle would have turned port, or if port being fortified would have more resistance to turning? Any advice would be appreciated. If I can't drink it, perhaps I'll make a reduction port sauce (you can hear me wimpering) on some lamb chops.