I have a frame 6B machine with 32 MW generator. Recently, The unit was tripped due to IGV trouble. I tried to stroke the valve later and found it not at all responding to the command. During the troubleshooting, it was noticed that the pressure in the accumulator was not released after the trip and oil started spilling all around while removing the servo valve. We replaced the servo valve suspecting its failure and stroked the IGV successfully. Unfortunately, the same problem occurred while starting the machine, and tripped due to the same reason. IGV stroking does not work unless the accumulator pressure is released before proceeding to start the hydraulic pump. Actuator was tested using a high-pressure hand pump and found no leak at all. looking forward for help from the members. Thanks.