To operate the thumb on this machine you have to press the middle button on the display panel to activate the service port. Then use the rocker switch on your hand control to move thumb open and closed. If it doesnt work, be sure the light is on next to the activation button. There are a few flow settings that you can enter if you keep pressing the button, so be sure you only press it once, the light comes on, and the light is not flashing. Be sure the quarter turn valve located next to or on top of the hydraulic tank is in the 2 way position, not the one way position. If it is in the one way position the thumb will only operate in one direction. That is used if the excavator is used with a hydraulic breaker. The button does not normally click but it will beep and the light should light up red.