[paredown]

When they were steel, the chances of damage was less. I have resorted to taping the wrench faces now that everything is alu.

The other 'trick' is to tighten the bottom nut down a little tight, then the hand tighten the top nut down to that. Then hold the top nut steady, and back the bottom nut up tight to the top one. It seems easier to hold the clearance constant, since when you cinch down on the top nut, it does tend to compress both nuts down, and alter the clearance that you have tried to leave.

A second comment--sometimes if it feels as if there is no half-way between too tight and too loose (at which point i usually take the whole thing apart to ensure that I have not had a brain freeze and installed something incorrectly)--and particularly if it seems the point at which it binds is different side to side--is to check carefully that the cups are seated squarely in the head tube, and down tight to the frame. If the whole gizmo is not squarely compressing as you tighten, the binding will show up as a slight difference.

Third comment--if the headset is well-used and been left too loose, you also might get uneven feeling because of ball-bearing wear (also true just from wear(; if it had been left too tight you could get brinelling--a series of ball bearing shaped divots in the races that makes if feel 'clicky' when tight, so check balls and races carefully while assembling.