A close-up of the plate bearing, or support strip showing earlier damage from some exploratory chiseling. It's good to remember, at times like these, that future conservators, re-builders, will always consider what we do today, to be butchery.
More damage at the tail. The area between the hitch panel, just above the bearing strip, was filled with a thin shim, made of Beech, as well as some glue, discolored here, as a result of contact with the plate.
Here the strip is coming off (slowly) White vinegar, a thin blade, followed by wedges. The wedges are made of Sugar Pine, which is softer than the surrounding material.
Below; close-ups of the sound-board rim joint with the bearing strip removed.
Above I have drawn some lines, for clarity. The lowest line is the rim to case joint. Below that is the inside of the case, rising towards you. The middle line is the joint between the rim and the sound-board. The sound-board sits in a shallow rabbet. The broken line is the edge of the inner rim below (hidden).

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