Sorry, I assume it's a cast iron top Jim? or aluminum?
Are both slots on the table this way? It would help to know how much difference there is between the front and back of the slot. You may need to build a jig with a dial gauge attached to determine how much material needs to be removed. And if the whole slot is tapered or if it's just a burr towards the end causing the issue.
To a small child, the perfect granddad is unafraid of big dogs and fierce storms but absolutely terrified of the word “boo.” – Robert Brault