hello all,
I have a 2 stop hydro (TAC-20) that has a horrible noise inside the pistons. Almost seems as if the smaller piston is bottoming out inside the larger piston when it comes to land on the first floor. Then when it takes off to go up the pistons seem to bang violently together. My question is, I'm sure there has to be some type of check valve to regulate oil flow between pistons, but where in the world is the check valve located? Is it in the cylinder? Between the pistons? This is the type of piston:
Model: 6501CH3
Also if anyone has a mechanical schematic that would be helpful.

thanks in advance for any and all help!