tailstock clamp is tight and the tailstock still moves

Clamp lever on the brother's Logan comes up solid. Tailstock still creeps toward the headstock when I drill, maybe a sixteenth over a deep hole. The clamp bolt isn't stripped. I'm out of obvious.

The shoe under the bed is probably worn, or the bolt is clamping the lever and not the shoe. Take it off. Look at the bearing surface. A tight lever is not the same thing as a clamped shoe.

Shoe was glazed and crowned. Filed it flat, roughened it, put it back. Creep is gone in a one inch hole, which is as far as I was willing to test on someone else's machine. He can drill the long one.