Adjusted loose (I loosened it to make sure) the Y-axis drew almost 3 amps. Across the range of travel with less variance from ends to middle. Both of those were expected since the Y likely sees less travel than the X its likely to wear less. Since its heavier its loose gib current should be higher. I adjusted it to bracket 4 amps as well, although due to the heavier weight it might have needed to be a little higher. Its 4 amps median current across the range of travel its got less than a 1/4 amp of variation.
I don't know if this really is the correct way to adjust the gibs on a CNC Mill, but it sure makes sense. Obviously a lighter machine would require less current and a much heavier machine would require much more, but the principle makes sense.
Now to see if the chatter has improved. Well, after I make a new rear Y-Axis way cover. I still think its likely a problem in the X -axis lead screw assembly, but I have my fingers crossed. Especially since I have a few more 4140HT parts to machine for the current job.
One thing seems odd. I see less dither on the servos. I think the looser gibbs might have been causing it to over shoot from the mass of the table and saddle. Dither was never really bad (even on the scope it seemed acceptable), but sometimes I'd hear it for a for tiny fraction of a second on a stop with the spindle off. During testing right now I didn't hear it even once.