When you say piston, do you mean the plastic reservoir/housing where all the fluid is kept? If so, then it's quite tricky to remove. Take a flat-head screwdriver. You can even try to wrap it in a cloth (so you don't damage the plastic) and just go bit by bit around the reservoir. The rubber seal makes the reservoir seat pretty tight so the liquid doesn't leak. Also, be careful not to damage that seal!Dear JaysonM, thank you for detailed explanation.
But i cant pull out piston! I pull it with all force - it stop and its all.
I unscrew bronze colore screw - counter clockwise -without success.
As i understand white plastic top cant piston go out? I remove c-ring before...
The bronze screw on a side doesn't unscrew all the way! It's a pressure release screw. Just make a couple turns counter-clockwise until it stops and that's it. It's not removed from the hydraulic pump!