Ellis Walentine
...as I see it. Either rout it out as you suggest and replace the routed section, or take Tom's advice and chisel the backs of the slot and glue wedges in the sides facing the tail vise. Both will entail a fair amount of work. Personally, I'd probably take the challenge of the chisel-and-wedge solution, though chiseling and floating that much jarrah would not be terribly appealing to me.

I suppose you could make custom wooden dogs for the existing holes, with shanks that slant one way and faces that slant toward the tail vise. What a conversation piece those would make.

Ellis