If a valve moves, it moves. There is no reason why a valve would only open 20%. We are convinced that the valve needs to be recalibrated. Were they sure that the valve was completely closed when they calibrated the actuator?
I think it is a bad idea to test the bare valve. Because the valve and actuator should be tested and calibrated together by competent personnel.
If you do run into a problem with the bare valve, please let me know asap