The issue is to separate the glued on block from the arm blank that will be
an arm on a chair I'm building. Both pieces are to be salvaged. With a
piece of plywood and an after market fence it is simple to make the cut.
Picture 2 shows the block separated and both pieces are intact and not
damaged. The third picture shows both pieces after being cleaned up with a
hand plane ready for fitting on the chair.

Sometimes a plan comes together. :-)