Ever since I changed the shaft to the UST Mamiya Helium 5F4, this driver has really hit another gear! Because of the stability of the shaft, I have been able to move the adjustment cog from -1/D to -1/N. It really allows me to go after it and not worry about over cooking it left. I do get an occasional one that leaks a little right, but 80% or better are straight as an arrow.