The extruder had a few features the interfered with the free arms and needs the design tweak, printing will have to wait for that to be done. 

In the mean time I found a long standing bug in how the centering value was calculated and applied the center calculation. It was being calculated as the middle of the 2 hysteresis bounds. This turned out to be ok, but it was being applied after the bounding values. This meant that the upper value was always high, and the lower was always low. I am now getting much faster settling times with lower I gains.