Takeuchi TB016 pilot controls

Hey everyone just picked this machine up a few months back. Its a great machine but having some problems with the right hand control doesnt return to center on its own. Now my question is, is there any way of rebuilding these type of joystick controls? From my limited inspection of the controlls its monted on a set of 4 valves with a swash type plate to controll each function forward back left and right. It doesnt make it unusable but would be nice to rid this problem. Also attached a pic of...

Takeuchi TB016 pilot controls

Takeuchi TB016 pilot controls