I don't know anything about Embraer hydraulics or flight controls, but if it's similar to Boeing/Airbus you can do some additional troubleshooting by putting 1 hydraulic system on, then off and the next hydraulic system on. The flight control shouldn't move. If it moves one of the actuators is slightly misrigged and can force against the others. If on shutdown the bad actuator is the last to loose hydraulics, it can still force the control down.
Hydraulic damping should be done by all actuators on that flight control, so 1 bad one shouldn't be a problem.
Again, maybe EMB is different, but it's a start