Have a Hitachi EX120-3 which has a pressure pulsation in the line from the pilot pump. You can see the hydraulic line from the pump to the pilot filter twitch and feel it if you put your hand around it. It's always there and happens every 1-2 seconds. It is alot more noticable when machine is warmed up. Thought it might be the bypass on the pilot filter operating but replaced the filter and no change. Can anyone tell me if this is normal and whats the cause. The machine appears to be operating fine.