My gate latch post PT 4" x4" has sheared off at surface from the existing concrete that was anchoring it. It was rotted and cracked away at surface. How should I fix this? There appears to be about 12" diameter of concrete at 4" below grade and I have no way of knowing how deep it was set. I am just using my own hand and power tools. Is there a bracket available that I could anchor to the concrete and lag a post to it?