Ursviken Pullmax Optima 130 press brake retrofit with 4 axis backgage

Finally, got to test drive the pullmax_optima component with closed loop PID, only p set to 5. Left and right side sync nicely, but with loud groaning noise. This machine runs smooth and quiet when I run it open loop. I think what I'm seeing in halscope is a combination of untuned PID and non-linear hydraulics.

chan. 1 pwmgen.04.value = controls left ram servo valve (driven by j3.vel_pid.output)
chan. 2 pwmgen.05.value = controls right ram servo valve (driven by j4.vel_pid.output)
chan. 3 pwmgen.06.value = controls tonnage proportional valve; ultimately comes from a slider on my test gui.
chan. 4,5,6,9 are the discrete spool valve coil power outputs (cr-200 to cr-203)
chan. 7 j3-motor-pos-cmd ultimately comes from a slider on my test gui. This is the input to the pos_pid.command
chan. 8 j3-motor-vel-cmd is signal connecting pos_pid.output => vel_pid.command

I was hoping velocity PID will allow me to skip the low frequency dither these valves like; but now I'm thinking my lack of that dither is what is fighting my PID. I will try lowering the p value first in case 5 is actually too high, next step is adding that low frequency dither, probably via siggen or a custom component.