Sounds like something may have taken a static hit when you were disconnecting / re-connecting things. You can swap the axis cables on the Opti-Wiz, and see if the problem moves to the Y axis. If it does, then the problem isn't with the Opti-Wiz. Next, connect the wires to the Opti-Wiz the way they were originally, then swap the cables on the trackball's optical boards. If moving the ball left and right causes the cursor to move up and down, but moving the ball up and down does nothing, then its a wiring problem. If moving the ball left and right does nothing, but moving the ball up and down moves the cursor left and right, then one of the optical PCB's probably took a static discharge or power surge of some nature.