Edison case repair or replace?

[mjbarnes]

If I soak it or wet those corners will the glue loosen up? Hoping that doesn't cause problems for the wood.

[JeffR1]

Don't soak it, at least I wouldn't, by the time any sort of water penetrated the old glue to soften it, the oak will have absorbed too much _ probably so much where the oak would turn black.

I would take the cabinet apart so there is just the box left, and make use a properly sharp wood chisel.
Take small gentle strips off the corner using careful strikes with a wood mallet, once you get to the cross grain of the panel, it will come away easily.

This assumes that you plan on making a new one of course.