Speaking of charge pumps and all hydraulics be extremely careful. When looking for leaks in a pressurized system, always have goggles on and use a piece of cardboard. Keep you hands clear. A tiny pinhole leak maybe invisible to the naked eye. It can pierce your flesh. If it does, you are done. You have to go to the hospital. They have to do surgery in you. They cut you open to flush the oil out and sterilize. Failure to go to hospital to have this performed, you will have gangrene. That will result in something being amputated.
Never try to perform off the wall diagnostic technics. I once was working in a diesel and hydraulics shop. A tech had a New Holland skid steer with dead hydraulics. Tech came to me and asked what I thought. I said if nothing stands out to you after checking fluid level and new filter, put a gauge on the charge pump test port. Welp, He decided to ignore my instruction ( FIREABLE offense for a good reason). 3 minutes later, I hear it fire up. I think, No way does that guy have a gauge hooked up. I come from behind a truck to look. He has a rag wrapped around a blow gun shoved into the hydraulic reservoir. I screamed at him NO. He could here me over running engines. He hit the lever on that gun. It pressurized the tank forcing oil into the high pressure side of the pump. The skid steer had the neutral safety, parking brake,seat switch and seatbelt switch system bypassed by the hands of its owner. That system controls use of the engine starter and hydraulics by way of two dump valves in the pump. The right turn lever was left in the forward position because the tech was hanging onto it as he climbed out of the cab. Welp… Once the high side of the pump got that pressurized oil, that skid steer instantly pinned that tech against a cinderblock wa. I ran over and shut the engine off. He is screaming. Bunch of other techs are screaming at me to get it off of him. I said no, he might hemorrhage. He will pass out in a minute. He did. He got a flight downtown to Shock Trauma.