100-400 wide open sharpness

I just read this thread I found in another message about good copies of this lens. I'm sure all of us 100-400 owners have seen this.
http://forums.dpreview.com/...forums/read.asp?forum=1029&message=37176297

My lens is not as sharp wide open as it is stopped down and I wonder if this is something Canon Repair can help with or not. I was thinking/hoping that they can adjust the lens and/or calibrate it specifically to my body (T2i).

My thinking is that the difference between so-so and great copies may be in one or more of the lens elements themselves and my copy can't be improved. What do you think?