Hello, I have a Clark lpg cgc25, when full tilt is requested machine abruptly shuts off after making a screeching sound that seems to come from hydraulic manifold. Opened hydraulic tank cap while running machine and can see a good amount of oil being dumped back into the tank despite the fact that no hydraulic function is being requested. I am thinking there may be an issue with the main relief valve but am not 100 percent sure. Any ideas or suggestins would be greatly appreciated. Thank you in advance