so the issue is the player two buttons aren't working?
i just sort of breezed through your other thread...I'm not sure about this particular board, but you may have a separate harness for the player 2 buttons. just be sure the wires aren't broken or tore off all the way along to the board and the plugs at the end are in place on the main board. be sure they are properly oriented and not plugged in backwards or something silly like that.
most likely (99%) just a slight wiring issue, but be aware, at absolute worst, you have a problem with the input register of the board. it would be best in that case to send it off for repair. (or mame the cabinet)
if the joystick seems to want to return to "center" but the center is slightly up, there is likely an issue with the spring or the collar that keeps the joystick centered.
depending on the style/brand/type of joystick your switches might have leafs on them that push the tiny button down to activate the switch, just bend it down a little. to give the actuator part of the stick some room to move before clicking the button.