Try taking the cone just past tight, before you tighten the non-drive side locknut. The axle tends to slip with the locknut sometimes when your turning it, and when it's done the cone is in the right position. Make sure the Axle vise is real tight before you start too. I've had this problem with some older exage 600 hubs. That always seems to fix it. You might have to have a helper use a wrench on the drive side to hold the axle while you tighten the non-drive side to get it real good and tight.