I’m not the sharpest knife in the drawer, but mine did the same thing until I added a piece of MDF as my spoil board, since I refuse to “spoil my spoil board” (yeah laugh) MDF is (or was) cheap. I generally use a playing card to test the levelness of the board or piece being cut, lower the “Z” to just touch the card, and create drag. Start at the far left side, and jog your “X” right in inch increments all the way to the other side of the spoil board. (with the playing card under the bit) Is the tension on the playing card (feeling by hand) the same? If yes, put your piece of wood down, and do the same thing. Sounds like one of the other is off, and I bet its the spoil board, cause my right side had the same issue.