Servo Tuning Advice

I'm having a little trouble dialling in the z axis. It is a vertical axis run by a zero backlash lead screw with no counter balance. The Screw and nut have a fair amount of friction. Maybe I'm just hoping for to much, but I just can't seem to get the following error as good as I think it should be. The part of the move that is giving me the most trouble is the last half of the deceleration.

I ment to attach a picture but it was a little to large to be accepted


When you say "offset" do you mean the Bias? Yes I did try that, but the I term seems to do be having the same effect.

A negative -I term is just wrong (it cannot be a different sign than the P term)
Not only is it adding positive feedback, but if it winds up to the point that it bounds
it will cause a run-away due to an assumption in the PID comp that "I" is always positive

Here is another try, with the acceleration turned up a little more to try to make things a little more obvious. I think I will have to reduce it by at least 1/3 on this axis for real life. Also these are torque mode drives.
This plot has a little more FF2 which seems to realy bring out some oscilations at the transitions.

This is about as good as I can get it any suggestions?

Yes, heres a static error (250 uInch) in the middle that the Integral term should pull in
I would make the integral term larger until it gets unstable and then use about 1/2 to 1/3 of that amount. Seems like the deadband could be smaller as well just so it does not interfere with interpretation of the plots

Yes it is inches (not mm). I am not sure what to try to do about the steady state error. Turning off the dead band doesn't seem to affect it. Nothing seems to make much of a dent in it except more P, and I already have an awful lot of that. Is this a problem that is just inherant to torque mode setups? It just seems like I'm missing something. I do have another set of screws laying around with twice the pitch, any chance that could help?