I moved the levers up to the point that it looks like a bullhorn on one of my bikes when I had the same problem and that took care of the numbing. On another bike, I tilted the levers to point a little bit inwards which put most of the pressure on the middle of the palm. It took a lot of adjusting before I zeroed in on the most comfortable lever position for me. The quickest test you could try is to rotate the hbar so the levers points upward. It'll look funky for a while but if it works for you, then reposition the bar and levers. Let us know how it works out for you. I'm sure someone around here could use the info you could provide. thanks in advance...